Selective Assembly of Na,K-ATPase α2β2 Heterodimers in the Heart DISTINCT FUNCTIONAL PROPERTIES AND ISOFORM-SELECTIVE INHIBITORS

被引：32

作者：

Habeck, Michael

Tokhtaeva, Elmira ^{[4
,5
]}

Nadav, Yotam

Ben Zeev, Efrat ^{[2
]}

Ferris, Sean P. ^{[6
,9
]}

Kaufman, Randal J. ^{[6
,10
]}

Bab-Dinitz, Elizabeta ^{[1
]}

Kaplan, Jack H. ^{[7
]}

Dada, Laura A. ^{[8
]}

Farfel, Zvi ^{[1
,3
]}

Tal, Daniel M. ^{[1
]}

Katz, Adriana ^{[1
]}

Sachs, George ^{[4
,5
]}

Vagin, Olga ^{[4
,5
]}

Karlish, Steven J. D. ^{[1
]}

机构：

[1] Weizmann Inst Sci, Dept Biomol Sci, IL-7610001 Rehovot, Israel

[2] Weizmann Inst Sci, Israel Natl Ctr Personalized Med, IL-7610001 Rehovot, Israel

[3] Tel Aviv Univ, Sch Med, IL-6997801 Tel Aviv, Israel

[4] Univ Calif Los Angeles, Sch Med, Dept Physiol, Los Angeles, CA 90073 USA

[5] Vet Affairs Greater Los Angeles Healthcare Syst, Los Angeles, CA 90073 USA

[6] Univ Michigan, Sch Med, Dept Biol Chem, Ann Arbor, MI 48109 USA

[7] Univ Illinois, Dept Biochem & Mol Genet, Chicago, IL 60607 USA

[8] Northwestern Univ, Feinberg Sch Med, Div Pulm & Crit Care Med, Chicago, IL 60611 USA

[9] Univ Calif San Francisco, Dept Pathol, 513 Parnassus Ave,Hlth Sci West 451,Box 0102, San Francisco, CA 94143 USA

[10] Sanford Burnham Prebys Med Discovery Inst, Rm 7103,10901 N Torrey Pines Rd, La Jolla, CA 92037 USA

来源：

JOURNAL OF BIOLOGICAL CHEMISTRY | 2016年 / 291卷 / 44期

基金：

美国国家卫生研究院; 以色列科学基金会;

关键词：

SODIUM-POTASSIUM PUMP; CARDIAC NA/K ATPASE; NA+/K+-ATPASE; PICHIA-PASTORIS; K-ATPASE; ADHESION MOLECULE; CRYSTAL-STRUCTURE; ALPHA-2; ISOFORM; BETA-SUBUNIT; INTRAOCULAR-PRESSURE;

D O I：

10.1074/jbc.M116.751735

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The Na, K-ATPase alpha(2) subunit plays a key role in cardiac muscle contraction by regulating intracellular Ca2+, whereas alpha(1) has a more conventional role of maintaining ion homeostasis. The beta subunit differentially regulates maturation, trafficking, and activity of alpha-beta heterodimers. It is not known whether the distinct role of alpha(2) in the heart is related to selective assembly with a particular one of the three beta isoforms. We show here by immunofluorescence and co-immunoprecipitation that alpha(2) is preferentially expressed with beta(2) in T-tubules of cardiac myocytes, forming alpha(2)beta(2) heterodimers. We have expressed human alpha(1)beta(1), alpha(2)beta(1), alpha(2)beta(2), and alpha(2)beta(3) in Pichia pastoris, purified the complexes, and compared their functional properties. alpha(2)beta(2) and alpha(2)beta(3) differ significantly from both alpha(2)beta(1) and alpha(1)beta(1) in having a higher K0.5K+ and lower K0.5Na+ for activating Na, K-ATPase. These features are the result of a large reduction in binding affinity for extracellular K+ and shift of the E1P-E2P conformational equilibrium toward E1P. A screen of perhydro-1,4-oxazepine derivatives of digoxin identified several derivatives (e.g. cyclobutyl) with strongly increased selectivity for inhibition of alpha(2)beta(2) and alpha(2)beta(3) over alpha(1)beta(1) (range 22-33-fold). Molecular modeling suggests a possible basis for isoform selectivity. The preferential assembly, specific T-tubular localization, and low K+ affinity of alpha(2)beta(2) could allow an acute response to raised ambient K+ concentrations in physiological conditions and explain the importance of alpha(2)beta(2) for cardiac muscle contractility. The high sensitivity of alpha(2)beta(2) to digoxin derivatives explains beneficial effects of cardiac glycosides for treatment of heart failure and potential of alpha(2)beta(2)-selective digoxin derivatives for reducing cardiotoxicity.

引用

页码：23159 / 23174

页数：16

共 76 条

[71] Recombinant addition of N-glycosylation sites to the basolateral Na,K-ATPase β1 subunit results in its clustering in caveolae and apical sorting in HGT-1 cells [J].