Differential localization of G-proteins, G alpha o and G alpha i-1, -2, and -3, in polarized epithelial MDCK cells

MDCK cells were stably transfected with rat G alpha o cDNA and confluent polarized monolayers were analyzed by immunocytochemistry to compare the intracellular targeting of G alpha o with the localization of the endogenously expressed G alpha i subunits. Immunofluorescence confocal microscopy showed that G alpha o is targeted strictly to the lateral membrane. Immunolocalization of G alpha i-1, -2, and -3 showed that G alpha i-1 and -2 are confined to the cytoplasm and G alpha i-3 is found on the lateral membrane, in the cytoplasm, and faintly on the apical surface of these cells. Thus, the different pertussis toxin-sensitive G-proteins are differentially localized in polarized epithelial cells. (C) 1997 Academic Press.