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Membrane attachment of recombinant G-protein alpha-subunits in excess of beta gamma subunits in a eukaryotic
W F Simonds1, R M Collins, A M Spiegel
1Molecular Pathophysiology Branch, National Institute of Diabetes, Digestive and Kidney Diseases, Bethesda, MD 20892.
Abstract:
Recombinant cDNAs encoding the alpha-subunits of Gi1, Gi2, Gi3, Go and Gs were transfected into COS cells with the pCD-PS mammalian expression vector. Expression of each G alpha was verified using subtype-specific peptide antisera on immunoblots. Quantitative immunoblotting of alpha and beta subunits indicated: i) that there was no change in expression of endogenous beta subunits, and ii) overexpression of alpha subunits could achieve a ratio of alpha:beta greater than 25:1. Despite the excess of alpha over beta, the G alpha subunits were found predominantly in the membrane fraction. The results demonstrate that G alpha subunits can attach to the membrane independently of beta gamma subunits.