The short and long forms of the alpha subunit of the stimulatory guanine-nucleotide-binding protein are unequally redistributed during (-)-isoproterenol-mediated desensitization of intact S49 lymphoma cells

Eur J Biochem. 1994 Nov 15;226(1):193-9. doi: 10.1111/j.1432-1033.1994.tb20041.x.

Abstract

We report here that desensitization of the beta-adrenergic receptor-triggered transmembrane signalling in S49 wild-type lymphoma cells, induced by (-)-isoproterenol (1 microM), results in unequal intracellular redistribution of the splicing variants of the alpha subunit of the stimulatory guanine-nucleotide-binding regulatory (Gs alpha) protein (Gs alpha-short and Gs alpha-long) and alters the functional characteristics of the membrane-associated signal transduction complex. We found that two cellular pools of membranes, light-density membranes and plasma membranes prepared by sucrose-density-gradient centrifugation of cell homogenates differed in their content of Gs alpha splicing subforms and, moreover, that prolonged activation of the beta-adrenergic pathway induced intermembrane redistribution of the splicing variants of Gs alpha. Short (10 min) as well as prolonged (1 h) (-)-isoproterenol treatment of the cells shifted Gs alpha-short from light-density membranes to plasma membranes and increased the total amount of light-density membrane-bound Gs alpha-long; in parallel, the maximal (-)-isoproterenol-stimulated or AlF4(-)-stimulated adenylyl cyclase activities measured in the plasma membrane pools prepared from treated cells decreased. The functional characteristics of the membrane-bound Gs alpha pools were examined by a cyc(-)-reconstitutive adenylyl cyclase assay where extracts of the plasma membrane and light-density-membrane pools, respectively, were mixed with plasma membranes derived from the mutant S49 cell line, cyc-, lacking Gs alpha. The maximal cyc(-)-reconstitutive activities of the extracts prepared from light-density membranes of short-term as well as long-term desensitized cells increased compared to control cells. These findings may indicate differences in the functioning of the splicing variants of Gs alpha.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Animals
  • Cell Membrane / metabolism
  • Cyclic AMP / biosynthesis
  • GTP-Binding Proteins / chemistry*
  • GTP-Binding Proteins / metabolism
  • Isoproterenol / pharmacology*
  • Lymphoma / enzymology
  • Lymphoma / metabolism*
  • Mice
  • Tumor Cells, Cultured

Substances

  • Cyclic AMP
  • GTP-Binding Proteins
  • Adenylyl Cyclases
  • Isoproterenol