Identification of G-proteins in rat parotid gland plasma membranes and granule membranes: presence of distinct components in granule membranes

Nawab Ali, Devendra K. Agrawal, Peter Cheung

Research output: Contribution to journalArticle

6 Scopus citations


We have identified by immunoblotting and ADP-ribosylation by cholera toxin and pertussis toxin the presence of Mr 43 and 46 KDa G, and 39 and 41 KDa G;.. subunits in rat parotid gland plasma membranes but not in granule membranes. A Mr 28 KDa polypeptide that served as substrate for ADP-ribosylation by both cholera toxin and pertussis toxin was present exclusively in granule membranes. Photoaffinity crosslinking of [α-32P]GTP showed the presence of high molecular weight GTP-binding proteins (Mr 160,100 KDa) in granule membranes. Six low molecular weight GTP-binding proteins (Mr 21-28 KDa) were differentially distributed in both plasma membranes and granule membranes. The present study identifies various GTP-binding proteins in rat parotid gland plasma membranes and granule membranes, and demonstrates the presence of distinct molecular weight GTP-binding proteins in granule membranes. These granule-associated GTP-binding proteins may be involved in secretory processes.

Original languageEnglish
Pages (from-to)155-162
Number of pages8
JournalMolecular and Cellular Biochemistry
Issue number2
Publication statusPublished - Oct 1992


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