Adaptoriproteiinit

Adaptoriproteiinit, commonly referred to as adaptor proteins, are a diverse class of non-enzymatic proteins that mediate protein–protein interactions within cellular signaling and trafficking networks. They function as scaffolds, linking receptors to downstream effectors and organizing multi-protein complexes to enable efficient and specific signal transmission. Because they lack intrinsic catalytic activity, adaptoriproteiinit influence signaling by assembly, localization, and timing rather than by chemical modification of substrates.

Many adaptor proteins contain modular interaction domains that mediate binding to other proteins or lipids. Common domains include SH2 and SH3, which recognize phosphotyrosine residues and proline-rich motifs, respectively; PTB, PH, and PDZ domains; and various lipid-binding regions. These features allow adaptoriproteiinit to connect receptor activation at the cell surface to intracellular signaling cascades such as Ras–MAPK, PI3K–Akt, and JAK–STAT, as well as to coordinate endocytosis and cytoskeletal rearrangements.

Representative examples include Grb2, which couples receptor tyrosine kinases to SOS and Ras; Shc and Gab family adaptors; Crk and CrkL; and Cbl, which can function both as an adaptor and an E3 ubiquitin ligase. In membrane trafficking, adaptor protein complexes (such as AP-2) recognize cargo and recruit clathrin to drive vesicle formation. Adaptoriproteiinit are widely conserved and ubiquitously expressed, reflecting their central role in signaling networks.

Dysregulation or mutation of adaptoriproteiinit has been linked to cancer, immune disorders, and developmental anomalies, highlighting their importance as nodes of cellular regulation. Ongoing research seeks to map interaction networks, define specificity determinants, and identify therapeutic targets within adaptor-mediated pathways.