The activity of a kinase called Src is regulated by phosphorylation. The kinase
is inactivated by phosphorylation at a C-terminal tyrosine residue (Tyr 527) and
is activated by interaction with an activated RTK, which stimulates Src to
autophosphorylation a different tyrosine residue (Tyr416). Full activation of Src
requires removal of the inhibitory phosphate group and binding to an activated
RTK. Based on this information, which statement about the activity of Src kinase
is correct?
A. The kinase is active only when Tyr527 is dephosphorylated and Tyr416 is
phosphorylated.
B. The kinase is active only when Tyr416 is phosphorylated.
C. The kinase is active only when Tyr416 is dephosphorylated.
D. The kinase is active only when Tyr527 is phosphorylated and Tyr416 is
dephosphorylated.
E. The kinase is active only when Tyr527 is dephosphorylated.
F. The kinase is active only when Tyr527 is phosphorylated.