What is the role of GRB2 in insulin signaling, and how does it interact with IRS 1?

GRB2 binds to phosphorylated IRS 1 via its SH2 domain, linking it to downstream signaling molecules.

GRB2 inhibits IRS 1 by binding to it, preventing further signaling.

GRB2 dephosphorylates IRS 1, terminating the signal.

GRB2 phosphorylates IRS 1, enhancing its signaling capacity.