You are studying the desensitization of a seven transmembrane (7 TM) domain receptor Y in A549 ce… Show more You are studying the desensitization of a seven transmembrane (7 TM) domain receptor Y in A549 cells. Your hypothesis is that receptor Y gets phosphorylated on a serine residue in response to cell confluence, allowing for recognition by b-arrestin, a protein that is known to inhibit 7 TM receptors from activating G proteins. (a) What experiment could you propose to prove that Y is phosphorylated only in confluent cells? (b) What experiment could you propose to prove that Arrestin binding to Y is phosphorylation dependent? (c) Your experiment proves that arrestin binding to Y is phosphorylation dependent. Discuss two possible modes by which phosphorylation can influence recognition of Y by arrestin and how to experimentally differentiate between these two modes. • Show less