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Localization of Gi
proteins in the centrosomes and at the midbody: implication for their role in cell division
Correspondence to Hyeseon Cho: hcho{at}niaid.nih.gov; or John H. Kehrl: kehrl{at}niaid.nih.gov
At the plasma membrane, heterotrimeric G proteins act as molecular switches to relay signals from G proteincoupled receptors; however, G
subunits also have receptor-independent functions at intracellular sites. Regulator of G protein signaling (RGS) 14, which enhances the intrinsic GTPase activity of Gi
proteins, localizes in centrosomes, which suggests the coexpression of Gi
. We show expression of Gi
1, Gi
2, and Gi
3 in the centrosomes and at the midbody. Fluorescence resonance energy transfer analysis confirms a direct interaction between RGS14 and Gi
1 in centrosomes. Expression of GTPase-deficient Gi
1 results in defective cytokinesis, whereas that of wild-type or GTPase-deficient Gi
3 causes prolonged mitosis. Cells treated with pertussis toxin, with reduced expression of Gi
1, Gi
2, and Gi
3 or with decreased expression of RGS14 also exhibit cytokinesis defects. These results suggest that Gi
proteins and their regulators at these sites may play essential roles during mammalian cell division.
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