Indexed on: 01 Dec '79Published on: 01 Dec '79Published in: Lung
The subcellular localization of adenylate cyclase (ATP pyrophosphate lyase [cyclizing] EC 22.214.171.124) from predominantly alveolar tissue of rat lung was studied using isotonic and hypotonic homogenization and differential centrifugation. The fractions prepared under hypotonic conditions were further subfractionated by nonlinear sucrose gradient centrifugation. All fractions were assayed for adenylate cyclase, marker enzymes, and DNA. Only 5′-nucleotidase (EC 126.96.36.199, a plasma membrane marker enzyme for rat lung) paralleled the distribution of adenylate cyclase under both isotonic and hypotonic conditions (co-efficient of correlation = 0.94). It is concluded that this adenylate cyclase to a large extent but not exclusively is associated with the plasma membranes. Basal adenylate cyclase activity of plasma membrane fractions was stimulated 3.7 times by NaF (0.01 M). It was also stimulated by isoproterenol (55 µM), epinephrine (55 µM), prostaglandin E1 (0.03 mM), and prostaglandin E2 (0.03 mM).