Question

Given the information provided, would curve 1 or 2 in the graph correspond to the serine residue? (There is no more additional infirmation besides what is given in the problem and the graph)

Consider a signaling protein that can be phosphorylated by a dual-specificity protein kinase at two independent sites (one tyrosine and one serine residue), such that each site is phosphorylated in about 1% of the protein molecules under normal conditions Phosphorylation at the first site has a short half-life, since a fast tyrosine phosphatase removes the phosphate soon after the residue is phosphorylated, whereas dephosphorylation at the second site-carried out by a serine/threonine phosphatase-is relatively slow. Upon activation of a signaling pathway, the concentration of the dual- specificity kinase increases several-fold rapidly. The phosphorylation state of the tyrosine and serine residues following stimulation is compared in the following graph. Which curve (1 or 2) do you think corresponds to the serine residue? Write down 1 or 2 as your answer with proper explanation. Percentage of molecules phosphorylated o Time after stimulation (min)

Answer 1

Answer- the curve 2 at the graph correspond to serine residue because both the residue work multiply many fold after activation so the activation will affect both the residue in same manner. Curve 2 has longer half life in comparison of curve 1.