Abstract 1894 Enzymes, pseudoenzymes, and moonlighting proteins: diversity of functions in protein families

Protein superfamilies often contain members that share significant amino acid sequence and structural homology but vary in their functions. Two homologous enzymes can catalyze different reactions or act on different substrates. Moonlighting enzymes have additional, often noncatalytic, functions. Pseudoenzymes are proteins or domains that resemble catalytically active enzymes but have no catalytic activity. While many pseudoenzymes retain some aspects of the function of their catalytically active homologues, some have functions that are very different from other members of their protein families and appear to have evolved from ancient moonlighting proteins.