Principal Components Analysis (PCA) of interface conservation scores and sequence alignment statistics.

Data points in the plot correspond to the projection of a 6-dimensional vector representing the pairwise alignment of a query and homolog sequence onto a 2-dimensional space defined by the first and second principal components. Blue lines with red circles at their tips represent the axes of the original 6-dimensional space for the 6 variables used in PCA analysis: -log(E) (where is the -value), Identity Score (), Positive Score (), log(L) (where is local alignment length), alignment length fractions ( and , where and are the lengths of the query and homolog proteins, respectively). Each data point is colored according to its computed score, with higher score (red/orange) indicating higher interface conservation and lower scores (blue/green) indicating lower interface conservation. The large gray arrow indicates the direction of increasing degree of interface conservation, from Dark to Twilight to Safe Zone.