Question

Which of the following are NOT TRUE about tyrosine kinase-associated receptors?

a. they bind to tyrosine kinases

b. the alpha interferon receptor is an example of a tyrosine kinase-associated receptor.

c. ligand binding results in phosphorylation of the cytoplasmic tails of the receptors on tyrosines

d. they have tyrosine kinase domains

Answer 1

Receptor tyrosine kinase (RTK) are the second largest class of receptors after G protein. Example of RTK includes insulin receptor, epidermal growth factor receptor, intracellular non-receptor tyrosine kinase (Janus kinase). Janus kinase are the receptor for most of the cytokines including alpha interferon. RTK have two cytosolic domains which forms a dimer upon binding of ligand and phosphorylate each other's. The phosphorylation occurs on in the tyrosine residues because both the cytosolic domains have intrinsic kinase activity.

Hence option A is incorrect, RTK does not binds to tyrosine kinases they itself has this activity intrinsically.