Predicting oligomerization states of coiled coils.

An algorithm based on the profile method was developed that faithfully distinguishes between the amino acid sequences of dimeric and trimeric coiled coils. Normalized sequence profiles derived from nonhomologous, two- and three-stranded, coiled-coil sequences with unambiguous registers were used to assign dimer and trimer propensities to test sequences. The difference between the dimer and trimer profile scores accurately reflected the preferred oligomerization state. The method relied on two strategies that may be generally applicable to profile calculations--profile values of solvent-exposed residues and of amino acids that were underrepresented in the data-base were given zero weight. Differences between the dimer and trimer profiles revealed sequence patterns that match and extend experimental studies of oligomer specification.