Modifications induced by acylphosphatase in the functional properties of heart sarcolemma Na+,K+ pump

FEBS Letters

Nassi, Paolo¹  Ramponi, Giampietro¹  Nediani, Chiara¹  Fiorillo, Claudia¹  Liguri, Gianfranco¹  Marchetti, Elena¹ 

[1] Dipartimento di Scienze Biochimiche, Università di Firenze, Viale Morgagni 50, 50134 Florence, Italy

关键词: Heart sarcolemma;    Na+;    K+-ATPase;    Sodium pump;    Acylphosphatase;    Na+;    K+-ATPase;    sodium-potassium ion-dependent adenosine triphosphatase;    EP;    the phosphorylated form of Na+;    K+-ATP-ase;   

DOI  :  10.1016/0014-5793(94)80639-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Acylphosphatase purified from cardiac muscle actively hydrolyzes the phosphoenzyme intermediate of heart sarcolemma Na⁺,K⁺-ATPase. This effect occurred with acylphosphatase amounts (up to 800 membrane protein) that fall within the physiological range and the low value of the apparent K _m (0.69 × 10⁻⁷ M) indicates a considerable affinity of the enzyme towards this specific substrate. Acylphosphatase addition to purified sarcolemmal vesicles significantly increased the rate of Na⁺,K⁺-dependent ATP hydrolysis. Maximal stimulation, observed with 800 protein, resulted in an ATPase activity which was about 2-fold over basal value. The same acylphosphatase amounts significantly stimulated, in a similar and to an even greater extent, the rate of ATP driven Na⁺ transport into sarcolemmal vesicles. These findings lead to suppose that an accelerated hydrolysis of the phosphoenzyme may result in an enhanced activity of heart sarcolemmal Na⁺,K⁺ pump, therefore suggesting a potential role of acylphosphatase in the control of this active transport system.

【 授权许可】

Unknown