来自牛腮腺富含质膜部分的Ca(2+)-ATP酶可能是胞外Ca(2+)依赖性核苷三磷酸酶。

The possibility that Ca(2+)-ATPase from the plasma membrane-rich fraction of bovine parotid gland is ecto-Ca(2+)-dependent nucleoside triphosphatase.

Sato J, Matsukawa R, Takiguchi H

Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan.

Int J Biochem. 1994 Jul;26(7):905-11. doi: 10.1016/0020-711x(94)90084-1.

Abstract

Parotid plasma membrane nonpump low-affinity Ca(2+)-ATPase, which possesses high-affinity (Ca2+ + Mg2+)-ATPase activity, was characterized. 2. Purified Ca(2+)-ATPase hydrolyzed the nucleoside triphosphates, GTP, ITP, CTP, UTP, TTP (67-93% of ATP) and nucleoside diphosphates, ADP, GDP, IDP, CDP, TDP (12-40% of ATP) but not AMP and p-NPP. 3. The maximum activities of Ca(2+)- and (Ca2+ + Mg2+)-ATPases were obtained in the presence of 1 mM and 0.13 microM Ca2+, respectively. 4. The Km values for Ca2+ in Ca(2+)- and (Ca2+ + Mg2+)-ATPases were 0.2 mM and 22 nM, respectively. 5. The activities of both Ca(2+)- and (Ca2+ + Mg2+)-ATPases were found in the right-side-out-vesicles obtained from the plasma membrane-rich fraction. 6. These features suggest that Ca(2+)-ATPase is an ecto-Ca(2+)-dependent nucleoside triphosphatase.

摘要

对腮腺质膜非泵低亲和力Ca(2 +)-ATP酶进行了表征，该酶具有高亲和力的(Ca2 + + Mg2 +)-ATP酶活性。2. 纯化的Ca(2 +)-ATP酶可水解核苷三磷酸，如GTP、ITP、CTP、UTP、TTP(为ATP的67 - 93%)以及核苷二磷酸，如ADP、GDP、IDP、CDP、TDP(为ATP的12 - 40%)，但不能水解AMP和对硝基苯磷酸酯。3. Ca(2 +)-ATP酶和(Ca2 + + Mg2 +)-ATP酶的最大活性分别在1 mM Ca2 +和0.13 microM Ca2 +存在的情况下获得。4. Ca(2 +)-ATP酶和(Ca2 + + Mg2 +)-ATP酶中Ca2 +的Km值分别为0.2 mM和22 nM。5. 在从富含质膜的部分获得的外翻小泡中发现了Ca(2 +)-ATP酶和(Ca2 + + Mg2 +)-ATP酶的活性。6. 这些特征表明Ca(2 +)-ATP酶是一种胞外Ca(2 +)依赖性核苷三磷酸酶。