AP BIOLOGY

Detailed explanation-1: -Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins? Receptor tyrosine kinase activity.

Detailed explanation-2: -Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones.

Detailed explanation-3: -General mechanism of action. It is admitted that the binding of a dimeric ligand to its receptor chains increases the proximity or/and stabilises the receptor chains that will be then auto-phosphorylated through their kinase domains (a process called trans-phosphorylation).

Detailed explanation-4: -Tyrosine kinases are important mediators of this signal transduction process, leading to cell proliferation, differentiation, migration, metabolism and programmed cell death. Tyrosine kinases are a family of enzymes, which catalyzes phosphorylation of select tyrosine residues in target proteins, using ATP.

Detailed explanation-5: -RTKs are single-pass, type I receptors resident in the plasma membrane. Generally, RTKs are activated through ligand-induced oligomerization, typically dimerization, which juxtaposes the cytoplasmic tyrosine kinase domains [3].