Low molecular mass GTP-binding proteins of adrenal chromaffin cells are present on the secretory granule.
Adrenal medullary homogenates and chromaffin granule membranes were separated by SDS-polyacrylamide gel electrophoresis and GTP-binding proteins detected using [alpha-32P]GTP binding to nitrocellulose blots. Four GTP-binding polypeptides of 24, 22, 20 and 18 kDa were routinely found in medullary homogenates and all were also found in isolated chromaffin granule membranes. The GTP-binding polypeptides co-sedimented with granule membrane markers following separation on sucrose gradients. On the basis of trypsin sensitivity and resistance to extraction, the GTP-binding proteins appeared to be tightly bound to the cytoplasmic surface of the granules. One or more of the secretory granule GTP-binding proteins could be involved in exocytosis in adrenal chromaffin cells.
Burgoyne
R D
RD
Department of Physiology, University of Liverpool, England.
Morgan
A
A
D000313:Adrenal Medulla / Q000032:analysis* / Q000648:ultrastructure; D000818:Animals; D002417:Cattle; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D002837:Chromaffin Granules / Q000032:analysis* / Q000648:ultrastructure; D002838:Chromaffin System / Q000032:analysis*; D019204:GTP-Binding Proteins / Q000032:analysis* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000032:analysis; D014357:Trypsin / Q000494:pharmacology
D006160:Guanosine Triphosphate; D014357:Trypsin; D019204:GTP-Binding Proteins