The KIND module: a putative signalling domain evolved from the C lobe of the protein kinase fold

A novel putative interaction domain - KIND (kinase non-catalytic C-lobe domain) - has been identified as being similar to the C-terminal protein kinase catalytic fold (C lobe). Its presence at the N terminus of signalling proteins and the absence of the active-site residues in the catalytic and activation loops suggest that it folds independently and is likely to be non-catalytic. The occurrence of the novel domain only in metazoa implies that it has evolved from the catalytic protein kinase domain into an interaction domain possibly by keeping the substrate-binding features.