In human adipocyte plasma membranes, pertussis toxin catalysed the ADP-ribosylation of an apparently single 40 kDa protein. The same protein was also observed in Western blots by using an antibody which identifies the C-terminal decapeptide of Gi alpha (alpha subunit of Gi). In analogous experiments, cholera toxin and an antibody raised against the C-terminal decapeptide of Gs alpha (alpha subunit of Gs) were used to identify two proteins of 42 and 45 kDa, the former of which was more prominent. A method was developed to estimate the relative amounts of Gi and Gs in crude adipocyte plasma membranes in a single immunoblot by using the two antisera. In animal models, changes in the amounts of G-proteins have been suggested to explain alterations in hormone-responsiveness in hypothyroidism and obesity. However, the amounts of Gi and Gs were unaltered in thyroidectomized papillary-carcinoma patients who had been without hormone substitution for 4 weeks. In adipocyte plasma membranes prepared from markedly obese subjects, the amounts of both Gi alpha and Gs alpha as calculated per mg of protein were decreased, but the Gi/Gs ratio remained unaltered in comparison with control subjects.
Research Article|June 15 1989
Guanine-nucleotide-binding proteins Gi and Gs in fat-cells from normal, hypothyroid and obese human subjects
J J Ohisalo;
J J Ohisalo
*Molecular Pharmacology Group, Department of Biochemistry, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.
†Department of Medical Chemistry, University of Helsinki, Siltavuorenpenger 10 A, SF-00170 Helsinki, Finland.
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Biochem J (1989) 260 (3): 843-847.
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J J Ohisalo, G Milligan; Guanine-nucleotide-binding proteins Gi and Gs in fat-cells from normal, hypothyroid and obese human subjects. Biochem J 15 June 1989; 260 (3): 843–847. doi: https://doi.org/10.1042/bj2600843
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