Question

Transphosphorylation of receptor tyrosine kinases:

activates JAK2

inhibits catalytic activity

generates binding sites for signaling molecules

triggers release of ligand

Answer 1

Answer-

Transphosphorylation of receptor tyrosine kinases generates binding sites for signaling molecules.

Like cytokine receptors, RTKs signal through a protein tyrosine kinase. Cytokine receptors associate with a separate cytosolic kinase protein, JAK (Janus kinase). But RTKs have an intrinsic kinase as part of their cytosolic domain. Ligand induced dimerization and activation of RTK stimulates its tyrosine kinase activity, which triggers intracellular signaling pathways like activation of SH3 domain of cytosolic adaptor protein, grb2. It then activates Ras protein.