In molecular biology and cell biology, an adapter protein is a type of protein molecule that assists in bringing together other proteins or molecules. Adapter proteins play important roles in signal transduction pathways, which are essential for cell communication, differentiation, and proliferation.
Adapter proteins typically have one or more specific domains that recognize and bind to other proteins or molecules. For example, some adapter proteins have SH2 domains that bind to phosphorylated tyrosine residues on other proteins, while others have PDZ domains that bind to short amino acid sequences on other proteins.
By bringing together multiple proteins or molecules, adapter proteins can facilitate the formation of larger signaling complexes and enhance the specificity and efficiency of signaling events. For example, adapter proteins can mediate the recruitment of downstream signaling molecules to activated receptors, leading to the activation of downstream signaling pathways.
Some examples of adapter proteins include Grb2, which plays a role in signaling downstream of receptor tyrosine kinases, and the scaffolding protein AKAP, which organizes signaling molecules in the vicinity of specific cellular compartments. Dysfunction or dysregulation of adapter proteins can lead to various diseases, including cancer and neurological disorders.