AP BIOLOGY

Detailed explanation-1: -For example, the insulin receptor and IGF1-receptor are expressed on the cell surface as disulfide-linked ()2 dimers (Ward et al., 2007). Binding of insulin or IGF1 induces structural changes within these dimeric receptors that stimulate tyrosine kinase activity and cell signaling.

Detailed explanation-2: -Receptor tyrosine kinases (RTKs) are a group of membrane-bound receptors that play an important role in the normal function of cells. They act as signal transducers that mediate cell-to-cell communication by phosphorylating tyrosine residues on key intracellular substrate proteins.

Detailed explanation-3: -RTKs are all synthesized as single-pass transmembrane proteins and bind polypeptide ligands, mainly growth factors. It has long been thought that all RTKs, except for the insulin receptor (IR) family, are activated by ligand-induced dimerization of the receptors.

Detailed explanation-4: -Receptor tyrosine kinases (RTKs) conduct biochemical signals via lateral dimerization in thwe plasma membrane, and their transmembrane (TM) domains play an important role in the dimerization process.

Detailed explanation-5: -Signal transduction Through diverse means, extracellular ligand binding will typically cause or stabilize receptor dimerization. This allows a tyrosine in the cytoplasmic portion of each receptor monomer to be trans-phosphorylated by its partner receptor, propagating a signal through the plasma membrane.