| 7627138 |
Vidal M, Lefevre F, Rouot B, Sainte-Marie J, Philippot J: A GTP-binding protein modulates a Ca2+ pump present in reticulocyte endocytic vesicles. Biochem Mol Biol Int. 1995 Apr;35(4):889-98.
Rat reticulocytes were used to prepare endocytic vesicles to study calcium fluxes across the endosomal membrane. We used 45Ca2+, and found that endocytic vesicles from reticulocytes present a Ca (2+)-ATPase that pumps Ca2+ into the lumen of vesicles. This activity was sensitive to vanadate and the calmodulin antagonists: trifluoperazine and calmidazolium. Western blot analysis using a monoclonal antibody evidenced that Ca (2+)-ATPase present in reticulocyte endocytic vesicles is probably the same as the erythrocyte Ca2+ pump. Ca2+ pump activity was shown to be partially inhibited by GTP gamma S. Moreover, mastoparan and benzalkonium chloride, both activators of heterotrimeric G proteins, were found to decrease 45Ca2+ uptake by endocytic vesicles. These results suggest the involvement of a trimeric G protein in the modulation of Ca (2+)-ATPase. |
82(1,1,1,2) |