Adaptor proteins play crucial roles in signal transduction by facilitating the assembly of multi-protein complexes and physically connecting different signalling components. They act as molecular bridges, linking receptors, enzymes, and other signalling molecules to ensure efficient and specific signal transmission. Adaptor proteins generally contain specific protein-binding domains enabling their interaction with specific signalling molecules. These domains include: Src homology 2 (SH2) domains, Src homology 3 (SH3) domains, phosphotyrosine-binding (PTB) domains, and protein interaction modules like PDZ domains and WW domains. Through these domains, adaptor proteins recognize phosphorylated residues, proline-rich motifs, or other specific protein motifs, facilitating the formation of protein-protein complexes. A key example of an adaptor protein is Grb2 (Growth Factor Receptor-Bound protein 2). Grb2 plays a crucial role in the signalling pathways downstream of receptor tyrosine kinases (RTKs). It consists of an SH2 domain and two SH3 domains, binding to phosphotyrosine residues on activated RTKs via its SH2 domain. Concomitantly, Grb2 interacts with other signalling proteins via its SH3 domains, including SOS (Son of Sevenless), an exchange factor for Ras family GTPases. The association of Grb2 with SOS then promotes the activation of the Ras-MAPK signalling pathway, regulating cellular proliferation, differentiation, and survival. Another important adaptor protein is Shc (Src Homology 2 domain-containing transforming protein). Shc also contains an SH2 domain, allowing it to bind to phosphotyrosine residues on activated RTKs. Once bound, Shc recruits and activates signalling proteins such as Grb2 and the protein tyrosine kinase growth factor receptor-bound protein 2 (Gab2). These interactions lead to the activation of downstream signalling pathways, including the Ras-MAPK pathway and the PI3K-Akt pathway, which regulate cell growth, survival, and metabolism. In immune signalling, the adaptor protein MyD88 (Myeloid Differentiation primary response gene 88) plays a critical role. MyD88 contains an SH2 domain and a Toll/interleukin-1 receptor (TIR) domain. It acts as an adaptor protein for Toll-like receptors (TLRs) and the interleukin-1 receptor (IL-1R) family. Upon ligand binding, TLRs and IL-1R recruit MyD88, facilitating recruitment of downstream signalling molecules, including kinases such as IRAK4 (Interleukin-1 receptor-associated kinase 4). This leads to the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs), triggering inflammatory responses and immune defence mechanisms. In the context of T cell receptor (TCR) signalling, the adaptor protein LAT (Linker for Activation of T cells) is critical for downstream signalling. LAT contains multiple tyrosine residues phosphorylated upon TCR engagement. These phosphorylated tyrosines act as docking sites for various signalling molecules including adaptor proteins such as Grb2, Gads (Grb2-related adaptor downstream of Shc), and SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) thereby promoting T cell activation and proliferation. Finally, adaptor proteins are also involved in intracellular trafficking pathways. AP-2 (Adaptor Protein Complex 2) is an adaptor protein that functions in clathrin-mediated endocytosis. AP-2 plays a crucial role in the internalization of transmembrane receptors and cargo proteins by forming a complex with clathrin and interacting with specific endocytic motifs on target proteins. This process is essential for the regulation of receptor signalling and cellular uptake of nutrients. We provide a comprehensive product range of research tools for studying adapters, including IRS1 antibodies, ICAM3 antibodies, Paxillin antibodies, IRS1 ELISA Kits, and TLR2 ELISA Kits. Explore our full adapters product range below and discover more, for less. Alternatively, you can explore our Cytoplasmic and Transmembrane product ranges.