+\subsubsection{The PCA Viewer}
+
+PCA analysis can be launched from the {\sl Calculate $\Rightarrow$ Principal
+Component Analysis} menu option. {\bf PCA requires a selection containing at
+least 4 sequences}. A window opens containing the PCA tool (Figure \ref{PCA}).
+Each sequence is represented by a small square, coloured by the background
+colour of the sequence ID label. The axes can be rotated by clicking and
+dragging the left mouse button and zoomed using the $\uparrow$ and $\downarrow$
+keys or the scroll wheel of the mouse (if available). A tool tip appears if the
+cursor is placed over a sequence. Sequences can be selected by clicking on them.
+[CTRL]-Click can be used to select multiple sequences.
+
+Labels will be shown for each sequence by toggling the {\sl View $\Rightarrow$
+Show Labels} menu option, and the plot background colour changed {\sl via} the
+{\sl View $\Rightarrow$ Background Colour..} dialog box. A graphical
+representation of the PCA plot can be exported as an EPS or PNG image {\sl via}
+the {\sl File $\Rightarrow$ Save As $\Rightarrow$ \ldots } submenu.
+
+\exercise{Principal Component Analysis}
+{ \exstep{Load the alignment at
+\textsf{http://www.jalview.org/tutorial/alignment.fa}.}
+\exstep{Select the menu option {\sl Calculate $\Rightarrow$ Principal Component
+Analysis}.
+A new window will open. Move this window within the desktop so that the tree,
+alignment and PCA viewer windows are all visible.
+Try rotating the plot by clicking and dragging the mouse on the plot in the PCA window.
+Note that clicking on points in the plot will highlight the sequences on the
+alignment.
+} \exstep{ Select {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$
+Neighbour Joining Using BLOSUM62}. A new tree window will appear.
+Place the mouse cursor on the tree window so that the
+tree partition location will divide the alignment into a number of groups, each of a different colour.
+Note how the colour of the sequence ID label matches both the colour of
+the partitioned tree and the points in the PCA plot.}
+{\bf See the video at:
+\url{http://www.jalview.org/training/Training-Videos}.}
+}
+
+\begin{figure}[hbtp]
+\begin{center}
+\includegraphics[width=2in]{images/PCA1.pdf}
+\includegraphics[width=3in]{images/PCA3.pdf}
+\caption{{\bf PCA Analysis.} }
+\label{PCA}
+\end{center}
+\end{figure}
+
+
+
+\subsubsection{PCA Data Export}
+Although the PCA viewer supports export of the current view, the plots produced
+are rarely suitable for direct publication. The PCA viewer's {\sl File} menu
+includes a number of options for exporting the PCA matrix and transformed points
+as comma separated value (CSV) files. These files can be imported by tools such
+as {\bf R} or {\bf gnuplot} in order to graph the data.
+
+\section{Trees}
+\label{trees}
+Jalview can calculate and display trees, providing interactive tree-based
+grouping of sequences though a tree viewer. All trees are calculated {\sl via}
+the {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$ \ldots} submenu.
+Trees can be calculated from distance matrices determined from \% identity or
+aggregate BLOSUM 62 score using either {\sl Average Distance} (UPGMA) or {\sl
+Neighbour Joining} algorithms. The input data for a tree is either the selected
+region or the whole alignment, excluding any hidden regions.
+
+On calculating a tree, a new window opens (Figure \ref{trees1}) which contains
+the tree. Various display settings can be found in the tree window {\sl View}
+menu, including font, scaling and label display options. The {\sl File
+$\Rightarrow$ Save As} submenu contains options for image and Newick file
+export. Newick format is a standard file format for trees which allows them to
+be exported to other programs. Jalview can also read in external trees in
+Newick format {\sl via} the {\sl File $\Rightarrow$ Load Associated Tree} menu
+option. Leaf names on imported trees will be matched to the associated alignment
+- unmatched leaves will still be displayed, and can be highlighted using the
+{\sl View $\Rightarrow$ Mark Unlinked Leaves} menu option.
+
+
+\begin{figure}
+\begin{center}
+\includegraphics[width=2.5in]{images/trees1.pdf}
+\includegraphics[width=2.5in]{images/trees2.pdf}
+\includegraphics[width=1.25in]{images/trees4.pdf}
+\caption{{\bf Calculating Trees} Jalview provides a range of options
+for calculating trees.
+Jalview can also load precalculated trees in Newick format (right).}
+\label{trees1}
+\end{center}
+\end{figure}
+
+
+Clicking on the tree brings up a cursor across the height of the tree. The
+sequences are automatically partitioned and coloured (Figure \ref{trees2}). To
+group them together, select the {\sl Calculate $\Rightarrow$ Sort $\Rightarrow$
+By Tree Order $\Rightarrow$ \ldots} alignment window menu option and choose the
+correct tree. The sequences will then be sorted according to the leaf order
+currently shown in the tree view. The coloured background to the sequence IDs
+can be removed with {\sl Select $\Rightarrow$ Undefine Groups} from the
+alignment window menu. Note that tree partitioning will also remove any groups
+and colourschemes on a view, so create a new view ([CTRL-T]) if you wish to
+preserve these.
+
+\begin{figure}
+\begin{center}
+\includegraphics[width=5in]{images/trees3.pdf}
+\caption{{\bf Interactive Trees} The tree level cutoff can be used to designate
+groups in Jalview.}
+\label{trees2}
+\end{center}
+\end{figure}
+
+%\subsubsection{Multiple Views and Input Data recovery from PCA and Tree Viewers}
+% move to ch. 3 ?
+%Both PCA and Tree viewers are linked analysis windows. This means that their selection and display are linked to a particular alignment, and control and reflect the selection state for a particular view.
+
+\subsubsection{Recovering input Data for a Tree or PCA Plot Calculation}
+\parbox[c]{5in}{
+The {\sl File $\Rightarrow$ Input Data } option will open a new alignment window containing the original data used to calculate the tree or PCA plot (if available). This function is useful when a tree has been created and then the alignment subsequently changed.
+}
+\parbox[c]{1.25in}{\centerline{\includegraphics[width=1.25in]{images/pca_fmenu.pdf}
+}}
+
+\subsubsection{Changing the associated View for a Tree or PCA Viewer}
+\parbox[c]{4in}{
+The {\sl View $\Rightarrow$ Associated Nodes With $\Rightarrow$ .. } submenu is shown when the viewer is associated with an alignment that is involved in multiple views. Selecting a different view does not affect the tree or PCA data, but will change the colouring and display of selected sequences in the display according to the colouring and selection state of the newly associated view.
+} \parbox[c]{3in}{\centerline{
+\includegraphics[width=2.5in]{images/pca_vmenu.pdf} }}
+
+\subsection{Tree Based Conservation Analysis}
+\label{treeconsanaly}
+
+Trees reflect the pattern of global sequence similarity exhibited by the
+alignment, or region within the alignment, that was used for their calculation.
+The Jalview tree viewer enables sequences to be partitioned into groups based
+on the tree. This is done by clicking within the tree viewer window. Once subdivided, the
+conservation between and within groups can be visually compared in order to
+better understand the pattern of similarity revealed by the tree and the
+variation within the clades partitioned by the grouping. The conservation based
+colourschemes and the group associated conservation and consensus annotation
+(enabled using the alignment window's {\sl View $\Rightarrow$ Autocalculated
+Annotation $\Rightarrow$ Group Conservation} and {\sl Group Consensus} options)
+can help when working with larger alignments.
+
+\exercise{Trees}
+{Ensure that you have at least 1G memory available in Jalview.
+
+{\sl (Start with link:
+\href{http://www.jalview.org/services/launchApp?jvm-max-heap=1G}{http://www.jalview.org/services/launchApp?jvm-max-heap=1G},
+or in the Development section of the Jalview web site
+(\href{http://www.jalview.org/development/development-builds}{http://www.jalview.org/development/development-builds})
+in the table, go to ``latest official build'' row and ``Webstart'' column, click
+on ``2G''.)}
+
+\exstep{Open the alignment at \textsf{http://www.jalview.org/tutorial/alignment.fa}.
+Select {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$ Neighbour
+Joining Using BLOSUM62}. A tree window opens.}
+\exstep{Click on the
+tree window, a cursor will appear. Note that placing this cursor divides the tree into a number of groups by colour.
+Place the cursor to give about 4 groups.}
+\exstep{In the alignment window, select
+{\sl Calculate $\Rightarrow$ Sort $\Rightarrow$ By Tree Order $\Rightarrow$ Neighbour Joining Tree using BLOSUM62 from... }. The sequences are
+reordered to match the order in the tree and groups are formed implicitly.
+Alternatively in the tree window, select {\sl View $\Rightarrow$ Sort Alignment
+by Tree}.}
+\exstep{Select {\sl Calculate $\Rightarrow$ Calculate Tree
+$\Rightarrow$ Neighbour Joining Using \% Identity}. A new tree window will
+appear. The group colouring makes it easy to see the differences between the two
+trees calculated by the different methods.}
+\exstep{Select from sequence 2
+column 60 to sequence 12 column 123. Select {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$ Neighbour Joining Using BLOSUM62}.
+ A new tree window will appear. The tree contains 11 sequences. It has been coloured according to the already
+ selected groups from the first tree and is calculated purely from the residues
+ in the selection.}
+
+Comparing the location of individual sequences between the three trees illustrates the importance of selecting appropriate regions of the
+alignment for the calculation of trees.
+
+{\bf See the video at:
+\url{http://www.jalview.org/training/Training-Videos}.}
+}
+
+\exercise{Pad Gaps in an Alignment}{
+\exstep{Open the alignment at \textsf{http://www.jalview.org/tutorial/alignment.fa}. In alignment window, ensure that the {\sl Edit $\Rightarrow$
+Pad Gaps } option is {\sl not} ticked, and insert one gap anywhere in the
+alignment.}
+\exstep{Select {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$
+Neighbour Joining Using BLOSUM62}.
+
+A warning dialog box {\bf ``Sequences not aligned'' } appears because the sequences input to the tree calculation are of different lengths. }
+
+\exstep{Select {\sl Edit $\Rightarrow$ tick Pad Gaps } and perform the
+tree calculation again. This time a new tree should appear - because padding
+gaps ensures all the sequences are the same length after editing.}
+{\sl Pad Gaps } option
+can be set in Preferences using
+{\sl Tool $\Rightarrow$ Preference $\Rightarrow$ Editing}.
+
+{\bf See the video at:
+\url{http://www.jalview.org/training/Training-Videos}.}
+}
+
+\exercise{Tree Based Conservation Analysis}{
+\label{consanalyexerc}
+\exstep{Load the PF03460 PFAM seed alignment using the sequence fetcher.
+Select {\sl Colour $\Rightarrow$ Taylor $\Rightarrow$ By Conservation}, set {\sl Conservation} shading threshold at around 20. }
+\exstep{Build a Neighbour joining tree using Select {\sl Calculate $\Rightarrow$ Calculate Tree $\Rightarrow$
+Neighbour Joining Using BLOSUM62}.}
+\exstep{Use the mouse cursor to select a point on the tree to partition the
+alignment into several sections.}
+\exstep {Select {\sl View $\Rightarrow$ Sort Alignment By Tree} option in the
+tree window to re-order the sequences in the alignment using the calculated
+tree.
+Examine the variation in colouring between different groups of sequences in the alignment
+window. }
+\exstep {You may find it easier to browse the alignment if you first uncheck the
+{\sl Annotations $\Rightarrow$ Show Annotations} option. Open the
+Overview Window within the View menu to aid navigation.}
+
+\exstep{Try changing the colourscheme of the residues in the alignment to
+BLOSUM62 (whilst ensuring that {\sl Apply Colour to All Groups} is selected).}
+{\sl Note: You may want to save the alignment and tree as a project file, since
+it is used in the next set of exercises. }
+
+{\bf See the video at:
+\url{http://www.jalview.org/training/Training-Videos}.}
+}
+
+
+\subsection{Redundancy Removal}
+
+The redundancy removal dialog box is opened using the {\sl Edit $\Rightarrow$ Remove Redundancy\ldots} option in the alignment menu. As its menu option placement suggests, this is actually an alignment editing function, but it is convenient to describe it here. The redundancy removal dialog box presents a percentage identity slider which sets the redundancy threshold. Aligned sequences which exhibit a percentage identity greater than the current threshold are highlighted in black. The [Remove] button can then be used to delete these sequences from the alignment as an edit operation\footnote{Which can usually be undone. A future version of Jalview may allow redundant sequences to be hidden, or represented by a chosen sequence, rather than deleted.}.
+\begin{figure}
+\begin{center}
+\includegraphics[width=5.5in]{images/redundancy.pdf}
+\end{center}
+\label{removeredundancydialog}
+\caption{The Redundancy Removal dialog box opened from the edit menu. Sequences that exceed the current percentage identity threshold and are to be removed are highlighted in black.}
+\end{figure}
+
+
+\subsection{Subdividing the Alignment According to Specific Mutations}
+
+It is often necessary to explore variations in an alignment that may correlate
+with mutations observed in a particular region; for example, sites exhibiting
+single nucleotide polymorphism, or residues involved in substrate recognition in
+an enzyme. One way to do this would be to calculate a tree using the specific
+region, and subdivide it in order to partition the alignment.
+However, calculating a tree can be slow for large alignments, and the tree may
+be difficult to partition when complex mutation patterns are being analysed. The
+{\sl Select $\Rightarrow$ Make groups for selection } function was introduced to
+make this kind of analysis easier. When selected, it will use the characters in
+the currently selected region to subdivide the alignment. For example, if a
+single column is selected, then the alignment (or each group defined on the
+alignment) will be divided into groups based on the residue or nucleotide found
+at that position. These new groups are annotated with the characters in the
+selected region, and Jalview's group based conservation analysis annotation and
+colourschemes can then be used to reveal any associated pattern of sequence
+variation across the whole alignment.
+
+
+% These annotations can be hidden and deleted via the context menu linked to the
+% annotation row; but they are only created on loading an alignment. If they are
+% deleted then the alignment should be saved and then reloaded to restore them.
+% Jalview provides a toggle to autocalculate a consensus sequence upon editing.
+% This is normally selected by default, but can be turned off for large alignments {\sl via} the {\sl Calculate $\Rightarrow$ Autocalculate
+% Consensus} menu option if the interface is too slow.
+
+% \subsubsection{Group Associated Annotation}
+% \label{groupassocannotation}
+% Group associated consensus and conservation annotation rows reflect the
+% sequence variation within a particular group. Their calculation is enabled
+% by selecting the {\sl Group Conservation} or {\sl Group Consensus} options in
+% the {\sl Annotation $\Rightarrow$ Autocalculated Annotation } submenu of the
+% alignment window.
+
+% \subsubsection{Alignment and Group Sequence Logos}
+% \label{seqlogos}
+
+% The consensus annotation row that is shown below the alignment can be overlaid
+% with a sequence logo that reflects the symbol distribution at each column of
+% the alignment. Right click on the Consensus annotation row and select the {\sl
+% Show Logo} option to display the Consensus profile for the group or alignment.
+% Sequence logos can be enabled by default for all new alignments {\sl via} the
+% Visual tab in the Jalview desktop's preferences dialog box.
+
+\section{Pairwise Alignments}
+Jalview can calculate optimal pairwise alignments between arbitrary
+sequences {\sl via} the {\sl Calculate $\Rightarrow$ Pairwise Alignments\ldots} menu option.
+Global alignments of all pairwise combinations of the selected sequences are performed and the results returned in a text box.
+
+
+
+\exercise{Remove Redundant Sequences}{
+
+\exstep{Using the alignment generated in the previous exercise (exercise
+\ref{consanalyexerc}).
+In the alignment window, you may need to deselect groups using Esc key.}
+
+\exstep{In the {\sl Edit} menu select {\sl Remove Redundancy} to open the
+Redundancy threshold selection dialog. Adjust the redundancy threshold value, start
+at 50 and increase the value to 65. Sequences selected will change colour in the Sequence ID panel. Select ``Remove'' to
+remove the sequences that are more than 65\% similar under this alignment.}
+
+\exstep{From the tree window, select {\sl View $\Rightarrow$
+Mark Unlinked Leaves} option, and note that the removed sequences are now prefixed with a * in the tree view.} \exstep{Use the [Undo] button in the Redundancy threshold selection dialog box
+to recover the sequences. Note that the * symbols disappear from the tree display.}
+\exstep{Experiment with the redundancy removal and observe the relationship between the percentage identity threshold and the pattern of unlinked nodes in the tree display.}
+}
+
+\exercise{Group Conservation Analysis}{
+\exstep{Re-use or recreate the alignment and tree which you worked with in the
+tree based conservation analysis exercise (exercise \ref{consanalyexerc}).}
+\exstep{In the {\sl View} menu in the alignment window, select {\sl New View} to
+create a new view. Ensure the annotation panel is displayed ({\sl Show annotation} in {\sl Annotations} menu). Enable the
+display of {\sl Group Consensus} option by checking {\sl Group Consensus} in the {\sl Annotation $\Rightarrow$
+Autocalculated Annotation } submenu in the alignment window.}
+\exstep{Displaying the sequence
+logos will make it easier to see the different residue populations within each
+group. Activate the logo by right clicking on the Consensus annotation row to
+open the context menu and select the {\sl Show Logo} option.}
+\exstep{In the column alignment ruler, select a column exhibiting about 50\%
+conservation that lies within the central conserved region of the alignment.
+(Column 74 is used in \href{https://youtu.be/m-PjynicXRg}{the Tree video}).}
+\exstep{Subdivide the alignment
+according to this selection using {\sl Select $\Rightarrow$ Make groups for selection}.}
+\exstep{Re-order the alignment according to the new groups that have been
+defined by selecting {\sl Calculate $\Rightarrow$ Sort $\Rightarrow$
+By Group}.
+
+Click on the group annotation row IDs to select groups exhibiting a
+specific mutation.}
+\exstep{Select another column exhibiting about 50\% conservation
+overall, and subdivide the alignment further. Note that the new groups
+inherit the names of the original groups, allowing you to identify the
+combination of mutations that resulted in the subdivision.}
+\exstep{Clear the groups, and try to subdivide the alignment using two
+non-adjacent columns.
+
+{\sl Hint: You may need to hide the intervening columns before you can select
+both of the columns that you wish to use to subdivide the alignment.}}
+\exstep{Switch back to the original view, and experiment with subdividing
+the tree groups made in the previous exercise.}
+{\bf See the video at:
+\url{http://www.jalview.org/training/Training-Videos}.}
+}
+
+\begin{figure}[]
+\begin{center}
+\includegraphics[width=4in]{images/pairwise.pdf}
+\caption{{\bf Pairwise alignment of sequences.} Pairwise alignments of three selected sequences are shown in a textbox.}
+\label{pairwise}
+\end{center}
+\end{figure}
+
+
+% To review, Chapter \ref{featannot} describes the mechanisms provided by
+% Jalview for interactive creation of sequence and alignment annotation, and how
+% they can be displayed, imported and exported and used to reorder the alignment. Chapter
+% \ref{featuresfromdb} discusses the retrieval of database references and
+% establishment of sequence coordinate systems for the retrieval and display of
+% features from databases and DAS annotation services.
+% Chapter \ref{msaservices} describes how to use the range of multiple alignment
+% programs provided by JABAWS, and Chapter \ref{aacons} introduces JABAWS AACon
+% service for protein multiple alignment conservation analysis.
+% In Chapter \ref{alignanalysis}, you will find
+% descriptions and exercises on building and displaying trees, PCA analysis,
+% alignment redundancy removal, pairwise alignments and alignment conservation
+% analysis.
+% Chapter \ref{wkwithstructure} introduces the structure visualization
+% capabilities of Jalview.
+% Chapter \ref{protsspredservices} explains how to perform protein secondary
+% structure predictions with JPred, and JABAWS protein disorder prediction
+% services are introduced in Chapter \ref{protdisorderpred}.
+% Chapter \ref{workingwithnuc} describes functions and visualization techniques
+% relevant to working with nucleotide sequences, coding region annotation and nucleotide
+% sequence alignments.
+% Chapter \ref{jvwebservices} introduces the various web based services
+% available to Jalview users, and Chapter \ref{jabaservices} explains how to
+% configure the Jalview Desktop for access to new JABAWS servers.
+
+
+% and Section \ref{workingwithrna} covers the visualization,
+% editing and analysis of RNA secondary structure.
+
+\chapter{Working with 3D structures}
+\label{3Dstructure}
+\label{wkwithstructure}
+Jalview facilitates the use of 3D structure data for the analysis of alignments
+by providing a linked view of structures associated with the aligned sequences.
+It also allows sequence, secondary structure and B-factor data to be imported
+from structure files, and supports the use of the EMBL-EBI's SIFTS database to
+construct accurate mappings between UniProt protein sequences and structures
+retrieved from the PDB.
+
+\section{Molecular graphics systems supported by Jalview}
+Jalview can interactively view 3D structure using Jmol, a Java based molecular
+viewing program\footnote{See the Jmol homepage \url{http://www.jmol.org} for
+more information.} integrated with Jalview.\footnote{Earlier
+versions of Jalview included MCView - a simple main chain structure viewer.
+Structures are visualized as an alpha carbon trace and can be viewed, rotated
+and coloured in a structure viewer and the results interpreted on a sequence
+alignment.} It also supports the use of UCSF Chimera, a powerful molecular
+graphics system that needs separate installation. Jalview can also read PDB and
+mmCIF format files directly to extract sequences and secondary structure
+information, and retrieve records from the European Protein
+Databank (PDBe) using the Sequence Fetcher (see \ref{fetchseq}).
+
+\subsection{Configuring the default structure viewer}
+\label{configuring3dviewer}
+To configure which viewer is used when creating a new
+structure view, open the Structures preferences window {\sl via} {\sl Tools $\Rightarrow$ Preferences\ldots} and
+select either JMOL or CHIMERA as the default viewer. If you select Chimera,
+Jalview will search for the installed program, and if it cannot be found,
+you will be prompted to locate the Chimera binary, or directed to the UCSF
+Chimera download page.
+
+\section{Automatic Association of PDB Structures with Sequences}
+Jalview can automatically determine which structures are associated with a
+sequence via its ID, and any associated database references. To do this, open
+the Sequence ID popup menu and select {\sl View 3D Structure}, to open the 3D
+Structure Chooser.
+%(Figure\ref{auto}).
+
+When the structure chooser is first opened, if no database identifiers are
+available, Jalview will attempt to discover identifiers for the sequence and from there discover any
+associated PDB structures. This can take a few seconds for each sequence and
+will be performed for all selected sequences. After this is done, you can see
+the added database references in a tool tip by mousing over the sequence
+ID\footnote{Tip:
+The sequence ID tooltip can often become large for heavily cross referenced sequence IDs. Use the {\sl View $\Rightarrow$ Sequence ID Tooltip $\Rightarrow$ }
+submenu to disable the display of database cross references or non-positional
+features. }, now shows the Uniprot ID and any associated PDB structures.
+%
+% \begin{figure}[htbp]
+% \begin{center}
+% %TODO fix formatting
+% \begin{center}
+% \includegraphics[width=3.5in]{images/pdbstructurechooser.pdf}
+% \end{center}
+%
+%
+% \caption{{\bf The PDB Structure Chooser dialog.} }
+% \label{auto}
+% \end{center}
+% \end{figure}
+
+\subsection{Drag-and-Drop Association of PDB Files with Sequences by Filename
+Match}
+\label{multipdbfileassoc}
+If one or more PDB files stored on your computer are dragged from their location
+on the file browser onto an alignment window, Jalview will search the alignment
+for sequences with IDs that match any of the files dropped onto the alignment.
+If it discovers matches, a dialog like the one in Figure
+\ref{multipdbfileassocfig} is shown, giving the option of creating associations
+for the matches.
+
+If no associations are made, then sequences extracted
+from the structure will be simply added to the alignment. However, if only
+some of the PDB files are associated, Jalview will raise another dialog box
+giving you the option to add any remaining sequences from the PDB structure files not present in
+the alignment. This allows you to easily decorate sequences in a newly imported
+alignment with any corresponding structures you've already collected in a directory
+accessible from your computer.\footnote{We plan to extend this facility in
+future so Jalview will automatically search for PDB files matching your
+sequence within a local directory. Check out
+\href{http://issues.jalview.org/browse/JAL-801}{Jalview issue 801}}
+
+% there is no mention of the other footnote (#3) that appears saying: Tip: The sequence ID tooltip can often become large for heavily cross-referenced sequence IDs. Use the ...
+% JBP: yes there is - under 'Discovery of ' subsection.
+\begin{figure}[htbp]
+\begin{center}
+\includegraphics[]{images/pdbdragdropassoc.pdf}
+
+\caption{{\bf Associating PDB files with sequences by drag-and-drop.} Dragging
+PDB files onto an alignment of sequences with names matching the dragged files
+names (A), results in a dialog box (B) that gives the option to associate each
+file with any sequences with matching IDs. }
+\label{multipdbfileassocfig}
+\end{center}
+\end{figure}
+
+
+\section{Viewing Structures}
+\label{viewAllStructures}
+The structure viewer is launched from the sequence ID context
+menu. To view a particular structure associated with a sequence in the
+alignment, select the sequence and right click the mouse to open context
+menu {\sl Structure $\Rightarrow$ 3D Structure data $\Rightarrow$} opens a Structure Chooser dialog box.
+The second way is most useful if you want to view all structural data available for
+a set of sequences in an alignment. Select all the sequence ids in the sequence
+ID panel and right click the mouse to open context
+menu {\sl Structure $\Rightarrow$ 3D Structure data $\Rightarrow$}. If any of
+the {\bf currently selected} sequences have structures associated they will
+appear in the Structure Chooser dialog box. The structures can be ranked by
+different parameters, 'Best Quality' is defaul option. Select the
+structures required and click {\sl View} to open a structure viewer containing
+the associated structures superposed according to the alignment.
+
+The structure to be displayed will be downloaded or loaded from
+the local file system, and shown as a ribbon diagram coloured according to the
+associated sequence in the current alignment view (Figure \ref{structure}
+(right)). The structure can be rotated by clicking and dragging in the structure
+window. The structure can be zoomed using the mouse scroll wheel or by
+[SHIFT]-dragging the structure.
+Moving the mouse cursor over a sequence to which the structure is linked in the
+alignment view highlights the respective residue's sidechain atoms. The
+sidechain highlight may be obscured by other parts of the molecule. Similarly,
+moving the cursor over the structure shows a tooltip and highlights the
+corresponding residue in the alignment. Clicking the alpha carbon or phosphorous
+backbone atom will toggle the highlight and residue label on and off. Often, the
+position highlighted in the sequence may not be in the visible portion of the
+current alignment view and the sliders will scroll automatically to show the
+position. If the alignment window's {\sl View $\Rightarrow$ Automatic Scrolling
+} option is not selected, however, then the automatic adjustment will be
+disabled for the current view.