A viral version of the Src kinase called v-Src is found in some retroviruses. Unlike the cellular Src, the v-Src kinase is constitutively active, and can drive the cell into uncontrolled growth and tumor formation. Which of the following molecular differences between the two versions of Src is more likely to be responsible for this?
A) v-Src lacks the active-site tyrosine residue.
B) v-Src lacks a lobe of the kinase domain.
C) v-Src has multiple inhibitory tyrosine phosphorylation sites in the kinase domain.
D) v-Src lacks the C-terminal tail that can bind to Src's SH2 domain.
E) v-Src has a longer C-terminal tail.

Question

Quizplus · Accepted Answer

By lacking the C-terminal tail that includes the inhibitory tyrosine phosphorylation site, v-Src bypasses the autoinhibitory mechanism mediated by the SH2 domain. Thus it no longer requires the dephosphorylation event to become active.

A Viral Version of the Src Kinase Called V-Src Is