Adaptor Proteins

Definition

Adaptor proteins are cell signaling molecules linking intracellular proteins, including cell surface receptors to cytosolic effectors.

Characteristics

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.

Adaptor proteins provide a diverse array of functions, including:

• 1. Co-localize signaling proteins in a specific area of the cell

• 2. Bring together enzymes and substrates to facilitate specific reactions

• 3. Coordinate diverse signals in a timely fashion

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.

In an oversimplified model, upon stimulation by extracellular ligands (e.g.,...