Distribution of beta-adrenergic binding in fractionated porcine adipocytes

1. The subcellular distribution of the porcine adipocyte beta-adrenergic receptor was studied in fractionated adipocytes. 2. The 30,000 g pellet obtained from hypotonically lysed cells contained membrane vesicles and mitochondria; it yielded approx 200-300 fmol dihydroalprenolol-bound receptors/mg protein. 3. Activity was increased to about 1000 fmol/mg protein after isolation of a plasma membrane fraction on a Percoll gradient. 4. The 5'-nucleotidase, succinate dehydrogenase and lactate dehydrogenase activities were usually enriched in compartments different from the ligand-binding activity. 5. Activity of porcine adipocyte 5'-nucleotidase, a purported plasma membrane marker enzyme, was not distributed in the same manner as the beta-adrenergic receptor.