Calmodulin stimulation of adenylate cyclase in rat brain membranes does not require GTP |
| |
Authors: | KB Seamon JW Daly |
| |
Institution: | Laboratory of Bioorganic Chemistry, Bldg. 4, Room 212 National Institute of Arthritis, Diabetes, and Digestive and Kidney Diseases National Institutes of Health, Bethesda, Maryland 20205, USA |
| |
Abstract: | Calcium stimulates adenylate cyclase activity in rat cerebral cortical membranes with either ATP or AppNHp as substrate. In contrast, isoproterenol stimulates the cerebral cortical enzyme with ATP as substrate but not with AppNHp as substrate unless exogenous GTP is added. In rat striatal membranes, calcium or dopamine stimulate adenylate cyclase activity with ATP as substrate, but not with AppNHp as substrate. GTP restores the dopamine but not the calcium response. The inhibitory guanine nucleotide GDP-βS antagonizes dopamine and GppNHp stimulation of the brain adenylate cyclases, but not stimulation by calcium of either rat cerebral cortical or striatal enzymes. Results indicate that GTP is not requisite to calcium-calmodulin activation of adenylate cyclases in brain membranes. In addition, calcium-calmodulin cannot activate striatal adenylate cyclases with a nonphosphorylating nucleotide, AppNHp, as substrate. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|