l - People

Sequence in the immediate neighborhood of a hinge was not found to be sufficient for
substantive hinge prediction by a GOR-like method, although the latter is successful at
predicting secondary structure. Similiarly, no particular sequential pairs of amino acid
types were found to be overrepresented in hinges. However, we did find that combining
amino acid propensity data with hinge propensities of active sites and secondary structure
yielded some predictive information. The prediction method we present can easily be
extended as additional hinge propensity data is reported. Indeed the publicly available
Hinge Atlas can be used not only to obtain such data but also to test the resulting
predictors. As an additional application, the Hinge Atlas can potentially be used to help
find hinges by homology. Although the hinges themselves are not conserved, the domain
cores should be, and therefore the hinges in the boundaries between domains may be
transferable by homology. We note, for instance, that a hinge occurring (unusually) in
the helix connecting the two EF hands of calmodulin has also been found in the
evolutionarily related Troponin C.
Conclusions
We found that the amino acids glycine and serine are more likely to occur in hinges,
whereas phenylalanine, alanine, valine, and leucine are less likely to occur. No evidence
was found for sequence bias in hinges by a GOR-like method, nor for propensity towards
sequential pairs of residues. Hinges tend to be small, but not hydrophobic or aliphatic.
They are found less often in α-helices, and more often in turns or random coils. Active
83