Abstract
We report here an assessment of the model refinement category of the
14th round of Critical Assessment of Structure Prediction (CASP14). As
before, predictors submitted up to five ranked refinements, along with
associated residue-level error estimates, for targets that had a wide
range of starting quality. The ability of groups to accurately rank
their submissions and to predict coordinate error varied widely. Overall
only four groups out-performed a “naïve predictor” corresponding to
resubmission of the starting model. Among the top groups there are
interesting differences of approach and in the spread of improvements
seen: some methods are more conservative, others more adventurous. Some
targets were “double-barrelled” for which predictors were offered a
high-quality AlphaFold 2 (AF2)-derived prediction alongside another of
lower quality. The AF2-derived models were largely unimprovable, their
apparent errors being found to reside very largely at domain and,
especially, crystal lattice contacts. Refinement is shown to have a
mixed impact overall on structure-based function annotation methods to
predict nucleic acid binding, spot catalytic sites and dock protein
structures.