The term<unk>  is prominent in literature regarding signal transduction, the process by which external stimuli regulate internal cellular functioning. The key to optimal cellular functioning is maintained by possessing specific machinery that can carry out tasks efficiently and effectively. Specifically, the process through which intermolecular reactions forward and amplify extracellular signals across the cell surface has developed to occur by two mechanisms. First, cell surface receptors can directly transduce signals by possessing both serine and threonine or simply serine in the cytoplasmic domain. They can also transmit signals through adaptor molecules through their cytoplasmic domain which bind to signalling motifs. Secondly, certain surface receptors lacking a cytoplasmic domain can transduce signals through ligand binding. Once the surface receptor binds the ligand it forms a<unk> mplex with a<unk> rresponding surface receptor to regulate signalling. These categories of cell surface receptors are prominently referred to as<unk> s.<unk> s are also referred to as accessory receptors, especially in the fields of biomedical research and immunology.<unk> s are proteins that maintain a three-dimensional structure. The large extracellular domains make up approximately 76–100% of the receptor. The motifs that make up the large extracellular domains participate in ligand binding and<unk> mplex formation. The motifs can include glycosaminoglycans, EGF repeats, cysteine residues or ZP-1 domains. The variety of motifs leads to<unk> s being able to interact with two to nine different ligands, which themselves can also interact with a number of different<unk> s. Most<unk> s lack a cytoplasmic domain and tend to be GPI-anchored, though a few receptors have been identified which<unk> ntain short cytoplasmic domains that lack intrinsic kinase activity.
Co-receptor
Preceptor
Lectin
K-complex
Fc receptor
Baroreceptor
Thromboxane receptor
Serpin