Phosphorylation of Tyr⁵²⁷ in the SH₂ Domain of Protein Tyrosine

Multiple Choice

Phosphorylation of Tyr⁵²⁷ in the SH₂ domain of protein tyrosine kinase pp60ᶜ⁻ˢʳᶜ inhibits tyrosine kinase activity.By which of the following mechanisms does it do this?

A) by moving an "activation loop" away from the active site
B) by moving an "activation loop" into the active site
C) by phosphorylating an "activation loop"
D) by covalent linkage to an "activation loop"