부산대학교 도서관

At the plasma membrane, heterotrimeric G proteins act as molecular switches to relay signals from G protein--coupled receptors; however, G[sub α] subunits also have receptor-independent functions at intracellular sites. Regulator of G protein signaling (RGS) 14, which enhances the intrinsic GTPase activity of G[sub iα] proteins, localizes in centrosomes, which suggests the coexpression of G[sub iα]. We show expression of G[sub iα1], G[sub iα2], and G[sub iα3] in the centrosomes and at the midbody. Fluorescence resonance energy transfer analysis confirms a direct interaction between RGS14 and G[sub iα1] in centrosomes. Expression of GTPase-deficient G[sub iα1] results in defective cytokinesis, whereas that of wild-type or GTPase-deficient G[sub iα3] causes prolonged mitosis. Cells treated with pertussis toxin, with reduced expression of G[sub iα1], G[sub iα2], and G[sub iα3] or with decreased expression of RGS14 also exhibit cytokinesis defects. These results suggest that G[sub iα] proteins and their regulators at these sites may play essential roles during mammalian cell division. [ABSTRACT FROM AUTHOR]