S100A7, S100A10, and S100A11 are transglutaminase substrates

S100 proteins are a family of 10-14 kDa EF-hand-containing calcium binding proteins that function to transmit calcium-dependent cell regulatory signal s, S100 proteins have no intrinsic enzyme activity but bind in a calcium-de pendent manner to target proteins to modulate target protein function, Tran sglutaminases are enzymes that catalyze the formation of covalent epsilon-( gamma -glutamyl)lysine bonds between protein-bound glutamine and lysine res idues, In the present study we show that transglutaminase-dependent covalen t modification is a property shared by several S100 proteins and that both type I and type II transglutaminases can modify S100 proteins. We further s how that the reactive regions are at the solvent-exposed amino- and carboxy l-terminal ends of the protein, regions that specify S100 protein function. We suggest that transglutaminase-dependent modification is a general mecha nism designed to regulate S100 protein function.