Guanine nucleotide-binding protein G(i) subunit alpha (GNAI3)

Heterotrimeric guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs) in numerous signaling cascades. The alpha chain contains the guanine nucleotide binding site and contrasts between an active, GTP-bound state and an inactive, GDP-bound state.

Signaling by an activated GPCR promotes GDP release and GTP binding. The alpha subunit has a low GTPase activity that converts bound GTP to GDP, thereby terminating the sign.