Muscarinic agents modify kinetics properties of membrane‐bound guanylyl cyclase activity

FEBS Letters

Alfonzo, M.¹  de Becemberg, I.Lippo¹  de Aguilar, A.E.Peña¹  de Alfonzo, R.Gonzalez¹  Camarillo, I.¹ 

[1] Sección de Biomembranas, Instituto de Medicina Experimental, Cátedras de Patología General y Fisiopatología, y Bioquímica, Facultad de Medicina, Universidad Central de Venezuela (UCV), Apartado 50587, Sabana Grande, Caracas, Venezuela

关键词: NaCl inhibition;    Muscarinic receptor;    Guanylyl cyclase;    Enzyme-receptor complex;    Plasma membrane;    (Tracheal smooth muscle);   

DOI  :  10.1016/0014-5793(89)80920-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Plasma membranes from bovine tracheal smooth muscle show guanylyl cyclase activity, which can be stimulated by muscarinic agonists such carbamylcholine and oxotremorine and blocked by atropine. This stimulation was observed in the presence of 150 mM NaCl. In the absence of this salt, guanylyl cyclase activity was considerably higher but was not affected by muscarinic agonists. Carbamylcholine decreased the apparent K _m but did not change the V _max of this enzyme. When plasma membrane fractions were extracted with 1% octylglucoside, guanylyl cyclase activity was preserved, however the muscarinic activation was abolished, despite a muscarinic receptor capable of [³H]quinuclidinylbenzilate binding being present in the extract. The detergent extraction changed the affinity of guanylyl cyclase for GTP but the Mn²⁺ kinetics was unaltered. Based on these findings and on current information in the literature, we propose that another component is required to restore the link between the muscarinic receptor and guanylyl cyclase, however the nature of this component remains to be established.

【 授权许可】

Unknown