title: Activated Gs alpha but not Gi alpha prevents the thermal inactivation of adenylyl cyclase in plasma membranes derived from S49 lymphoma cells.
abstract: The thermal inactivation of adenylyl cyclase was studied in plasma membranes isolated from wild-type and the mutant cell strain cyc- of S49 lymphoma. The half-life of adenylyl cyclase activity at 30 degrees C was decreased from 14.2 min to 3.4 min by the presence of detergents. ATP as well as forskolin prevented the adenylyl cyclase inactivation in a dose-response manner independent of the utilized type of cell membranes. Activation of G-proteins by GTP gamma S or by AlF-4 in wild-type membranes but not in cyc- membranes partially prevented adenylyl cyclase inactivation. Adenylyl cyclase activity in cyc- membranes was preserved in the presence of GTP gamma S or AlF-4 from the observed detergent-induced inactivation by complementation of these membranes with an extract from wild-type membranes. ADP-ribosylation of Gi alpha in cyc- membranes did not influence the kinetics of the inactivation process of adenylyl cyclase, whereas ADP-ribosylated Gs alpha protein protected adenylyl cyclase more effectively than non-ribosylated Gs alpha in wild-type plasma membranes when GTP was used as an activator.
authors.affiliation: Wallenberg Laboratory for Cardiovascular Research, University of Gothenburg, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Kvapil
authors.forename: J
authors.initials: J
authors.lastname: Novotny
authors.forename: L A
authors.initials: LA
authors.lastname: Ransnäs
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D005576:Colforsin / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008223:Lymphoma; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D003902:Detergents; D005576:Colforsin; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases