Departments of Biochemistry and Chemistry, University of Illinois, Urbana, IL 61801, USA. j-gerlt@uiuc.edu
The functional annotation of proteins identified in genome sequencing projects is based on similarities to homologs in the databases. As a result of the possible strategies for divergent evolution, homologous enzymes frequently do not catalyze the same reaction, and we conclude that assignment of function from sequence information alone should be viewed with some skepticism.