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. May play a role in cell division. G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. In this context, interacts with GNB2 (By similarity). Interacts with UNC5B (By similarity). Interacts with GPSM1 (By similarity). Interacts with RGS12 and RGS14 (By similarity). Interacts (inactive GDP-bound form) with NUCB1 (via GBA motif); the interaction leads to activation of GNAI3 (By similarity). Interacts (inactive GDP-bound form) with CCDC88C/DAPLE (via GBA motif) (By similarity). Interacts (inactive GDP-bound form) with CCDC8A/GIV (via GBA motif) (By similarity). Interacts with CXCR1 and CXCR2 (By similarity). Localizes in the centrosomes of interphase and mitotic cells. Detected at the cleavage furrow and/or the midbody (By similarity). Belongs to the G-alpha family. G(i/o/t/z) subfamily.