Evidence for G proteins in rat parotid plasma membranes and secretory granule membranes.
Biochem J
; 285 ( Pt 2): 441-9, 1992 Jul 15.
Article
en En
| MEDLINE
| ID: mdl-1637337
ABSTRACT
G proteins were identified in rat parotid plasma membrane-enriched fractions and in two populations of isolated secretory granule membrane fractions. Both [32P]ADP-ribosylation analysis with bacterial toxins and immunoblot analysis with crude and affinity-purified antisera specific for alpha subunits of G proteins were utilized. Pertussis toxin catalysed the ADP-ribosylation of a 41 kDa substrate in the plasma membrane fraction and both secretory granule membrane fractions. Cholera toxin catalysed the ADP-ribosylation of two substrates with molecular masses of 44 kDa and 48 kDa in the plasma membrane fraction but not in the secretory granule fractions. However, these substrates were detected in the secretory granule fractions when recombinant ADP-ribosylating factor was present in the assay medium. Immunoblot analysis of rat parotid membrane fractions using both affinity-purified and crude antisera revealed strong immunoreactivity of these membranes with anti-Gs alpha, -Gi alpha 1/alpha 2 and -Gi alpha 3 sera. In contrast Gs alpha was the major substrate found in both of the secretory granule fractions. Granule membrane fractions also reacted moderately with anti-Gi alpha 3 antiserum, and weakly with anti-Gi alpha 1/alpha 2 and -G(o) alpha sera. The results demonstrate that the parotid gland membranes express a number of G proteins. The presence of G proteins in secretory granule membranes suggests that they may play a direct role in regulating exocytosis in exocrine glands.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Glándula Parótida
/
Proteínas de Unión al GTP
/
Gránulos Citoplasmáticos
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Biochem J
Año:
1992
Tipo del documento:
Article