Novel components and enzymatic activities of the human erythrocyte plasma membrane calcium pump

FEBS Letters

Kosk-Kosicka, Danuta¹  Huang, Ruiping²  Reusch, Rosetta N² 

[1] Department of Anesthesiology/CCM, John Hopkins University School of Medicine, 600 Wolfe St., Blalock 1404, Baltimore, MD 21287-4961, USA;Department of Microbiology, Giltner Hall, Michigan State University, East Lansing, MI 48824, USA

关键词: Poly (3-hydroxybutyrate);    Polyphosphate;    Polyphosphate kinase;    Ca2+-ATPase;   

DOI  :  10.1016/S0014-5793(97)00863-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The plasma membrane Ca²⁺ pump is essential for the maintenance of cystolic calcium ion concentration levels in eukaryotes. Here we show that the Ca²⁺-ATPase, purified from human erythrocytes, contains two homopolymers, poly(3-hydroxybutyrate) (PHB) and inorganic polyphosphate (polyP), which form voltage-activated calcium channels in the plasma membranes of Escherichia coli and other bacteria. Furthermore, we demonstrate that the plasma membrane Ca²⁺-ATPase may function as a polyphosphate kinase, i.e. it exhibits ATP-polyphosphate transferase and polyphosphate-ADP transferase activities. These findings suggest a novel supramolecular structure for the functional Ca²⁺-ATPase, and a new mechanism of uphill Ca²⁺ extrusion coupled to ATP hydrolysis.

【 授权许可】

Unknown