GNAI2, also named as GNAI2B, belongs to the G-alpha family. G(i/o/t/z) subfamily. Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. GNAI2 is 93% homolog to GNAI1, 94% to GNAI3, 85% to GNAT3, 82% to GNAT2.