1 | INTRODUCTION
CASP has been monitoring progress
in the protein tertiary structure prediction for over 25 years1-4. Every other year
since 1994, CASP organizers contact a wide network of structural
biologists in quest of targets for the upcoming protein structure
modeling experiment. The latest CASP15 call yielded 93 single-sequence
entries representing monomeric proteins or subunits of protein
multimeric complexes
(https://predictioncenter.org/casp15/targetlist.cgi?view=regular).
Eighty-one entries on this list were suggested for tertiary structure
prediction, while the remaining twelve were auxiliary structures for
other prediction categories (see Table 1). Four targets out of the 81
were canceled due to the lack of structure at the time of evaluation,
leaving 77 for the assessment. Below we discuss procedures for splitting
these targets into evaluation units (EUs) and assigning them to
evolutionary-based prediction classes.
Defining and classifying evaluation units in CASP has been a very
important and time-consuming task requiring multiple numerical tests and
extensive human inspection. In five out of six recent CASPs these tasks
were directed by Lisa Kinch, whose involvement with the structural
classification ECOD database5 and extensive
knowledge of protein structure was an invaluable asset6-10. In CASP15 we
decided to develop a procedure that would mimic the procedure of
previous CASPs while requiring only minimal human intervention.