You are studying the signal-transduction pathways in a cell line derived from a breast cancer. Your studies identify a novel protein that specifically binds a phosphorylated tyrosine residue on the cytoplasmic aspect of a protein kinase-linked receptor. This binding anchors the protein near the cell surface. Which of the following domains is most likely to be responsible for this binding property?
A) α-helix
B) helix-loop-helix
C) β-pleated sheets
D) SH2
E) zinc finger

Question

Quizplus · Accepted Answer

The SH2 (Src Homology 2) domain is known for binding specifically to phosphorylated tyrosine residues on receptor tyrosine kinases, which aligns with the described function of the novel protein.  Many receptors that have intrinsic tyrosine kinase activity as well as the tyrosine kinases that are associated with cell surface receptors contain tyrosine residues that, upon phosphorylation, interact with other proteins of the signal-transduction cascade. These other proteins contain a domain of amino acid sequences that are homologous to a domain first identified in the SRC proto-oncogene. These domains are termed SH2 domains (SRC homology domain 2).

You Are Studying the Signal-Transduction Pathways in a Cell Line