Answer:
Option E
Explanation:
Complete question
A researcher is using a small molecule as an inhibitor to manipulate a signaling pathway. This inhibitor prevents phosphorylation and MOST likely targets a:
A) ligand-gated ion channel.
B) G protein-coupled receptor.
C) phosphatase.
D) G protein.
E) receptor kinase.
Solution
Receptor kinase is an enzyme that acts as a catalyst while transferring phosphate group to specific substrate thereby causing auto phosphorylation of tyrosine.
Phosphorylation occurs when receptor kinase binds to the ligands. Binding causes dimerization of receptor kinase which then phosphorylates tyrosine residues in the cytosolic domain.
The inhibitor molecule prevents phosphorylation therefore it must target the molecule responsible for causing tyrosine phosphorylation.
Hence, option E is correct
