New Measure Of Protein Stickiness

In the crowded environment of a cell, proteins need to avoid unwanted or nonfunctional interactions to do their jobs. A new scale of amino acid “stickiness” shows that highly abundant proteins have less sticky surfaces and that stickiness may play a role in protein evolution (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1209312109). To develop the scale, Emmanuel D. Levy, Subhajyoti De, and Sarah A. Teichmann of the U.K. Medical Research Council Laboratory of Molecular Biology calculated the frequency of amino acids appearing on the surfaces versus interior or interface regions of proteins in bacteria, yeast, and humans. Amino acids found predominately at surfaces, such as lysine or glutamate, were defined as “nonsticky,” and those found at interfaces, such as isoleucine or phenylalanine, were defined as “sticky.” The correlations the researchers observed were different from those obtained by common measures of hydrophobicity. The researchers note that the surfaces of highly abundant proteins tend to be evolutionarily conserved, indicating that organisms may preserve less sticky amino acids to help proteins avoid nonfunctional interactions.