G-proteins of fat-cells. Role in hormonal regulation of intracellular inositol 1,4,5-trisphosphate - PubMed (original) (raw)

G-proteins of fat-cells. Role in hormonal regulation of intracellular inositol 1,4,5-trisphosphate

P J Rapiejko et al. Biochem J. 1986.

Abstract

Pertussis toxin abolishes hormonal inhibition of adenylate cyclase, hormonal stimulation of inositol 1,4,5-trisphosphate accumulation in rat fat-cells, and catalyses the ADP-ribosylation of two peptides, of Mr 39,000 and 41,000 [Malbon, Rapiejko & Mangano (1985) J. Biol. Chem. 260, 2558-2564]. The 41,000-Mr peptide is the alpha-subunit of the G-protein, referred to as Gi, that is believed to mediate inhibitory control of adenylate cyclase by hormones. The nature of the 39,000-Mr substrate for pertussis toxin was investigated. The fat-cell 39,000-Mr peptide was compared structurally and immunologically with the alpha-subunits of two other G-proteins, Gt isolated from the rod outer segments of bovine retina and Go isolated from bovine brain. After radiolabelling in the presence of pertussis toxin and [32P]NAD+, the electrophoretic mobilities of the fat-cell 39,000-Mr peptide and the alpha-subunits of Go and Gt were nearly identical. Partial proteolysis of these ADP-ribosylated proteins generates peptide patterns that suggest the existence of a high degree of homology between the fat-cell 39,000-Mr peptide and the alpha-subunit of Go. Antisera raised against purified G-proteins and their subunits were used to probe immunoblots of purified Gt, Gi, Go, and fat-cell membrane proteins. Although recognizing the 36,000-Mr beta-subunit band of Gt, Gi, Go and a 36,000-Mr fat-cell peptide, antisera raised against Gt failed to recognize either the 39,000- or the 41,000-Mr peptides of fat-cells or the alpha-subunits of Go and Gi. Antisera raised against the alpha-subunit of Go, in contrast, recognized the 39,000-Mr peptide of rat fat-cells, but not the alpha-subunit of either Gi or Gt. These data establish the identity of Go, in addition to Gi, in fat-cell membranes and suggest the possibility that either Go or Gi alone, or both, may mediate hormonal regulation of adenylate cyclase and phospholipase C.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Biol Chem. 1978 Feb 10;253(3):671-8 - PubMed
    1. J Biol Chem. 1951 Nov;193(1):265-75 - PubMed
    1. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4 - PubMed
    1. Nature. 1980 Feb 7;283(5747):587-9 - PubMed
    1. J Biol Chem. 1980 Aug 10;255(15):7480-6 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources