What must happen for Src to become activated?
In inactive orm, tyrosine near the C terminus is phosphorylated and bound to the SH2 domain; and the SH3 is bound to an internal peptide that causes distortion of the active site.
1) The C-terminal phosphate must be removed, loosening the structure
2) The SH3 domain must be bound by a specific activating protein called Nef, which has a proline region. The kinase then is able to phosphorylate tyrosine to self-activate.
This signals the completion of a set of separate upstream events.