Small membrane-associated GTP-binding proteins of catecholamine-secreting cells.
1. Four GTP-binding proteins (23-27 kDa) were identified in membranes from PC12 cells by [alpha 32P]GTP binding to nitrocellulose blots of SDS-polyacrylamide gels. 2. The GTP-binding proteins remained associated with membranes during stimulation of intact cells by K(+)-depolarization or even after addition of Ca2+ to digitonin-permeabilized cells. 3. By two-dimensional gel electrophoresis, six GTP-binding proteins were resolved and based on their mobility, their phosphorylation state appeared independent of Ca2+. 4. Fractionation of PC12 membranes showed that these GTP-binding proteins were broadly distributed in post-nuclear membranes with the plasma membranes containing the highest specific GTP-binding activity. 5. Membrane fractions from bovine adrenal medulla contain similar GTP-binding proteins with GTP-binding intensity also being highest in the plasma membrane. 6. The GTP-binding proteins could be concentrated in the detergent-rich fraction upon Triton X-114 phase separation.
Rhoads
A R
AR
Department of Biochemistry and Molecular Biology, Howard University, College of Medicine, Washington, D.C. 20059.
Vu
N D
ND
Carroll
A G
AG
D000313:Adrenal Medulla / Q000737:chemistry / Q000166:cytology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry; D002837:Chromaffin Granules / Q000737:chemistry; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000302:isolation & purification*; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology; D013347:Subcellular Fractions
D002395:Catecholamines; D019204:GTP-Binding Proteins; D011188:Potassium; D002118:Calcium