Adaptor Proteins

Adaptor proteins are cell signaling molecules linking intracellular proteins, including cell surface receptors to cytosolic effectors. They play key roles in cellular signaling such as phosphorylation, dephosphorylation, signal transduction, organization of the cytoskeleton, cell adhesion, regulation of gene expression, all distinct yet interacting systems. In their pure form, adaptor proteins are devoid of any intrinsic enzymatic activity and serve as intracellular platforms for the amplification and coordinated assembly of multimeric protein complexes. A common feature of adaptor proteins is the organization in modular structures; a limited number of highly evolutionary conserved protein sequences ("domains" or "modules") are combined to produce a diverse array of protein structures with specific cellular functions and diverse connecting capabilities.