Moonlighting proteins: complications and implications for proteomics research

Proteomics projects involving biochemical, genetic and computational methods are being used to elucidate the functions of thousands of proteins in healthy and disease states. The results provide valuable information both for understanding basic physiological processes and for the development of novel therapeutics. However, the ability of a protein to moonlight, or to have more than one function, can complicate the interpretation and application of the results from these proteomics studies. This review provides examples of how moonlighting proteins can affect the results of proteomics projects being used to determine protein function based on patterns of protein expression, protein–protein interactions, analysis of protein sequences and structures, and other methods.