Restoration of phosphorylation capacity to the dormant half of the α‐subunits of Na+, K+‐ATPase

FEBS Letters

Liu, Guoquan¹  Xie, Zijian¹  Askari, Amir¹  Modyanov, Nikolai N.¹ 

[1] Department of Pharmacology, Medical College of Ohio, Toledo, OH 43699-0008, USA

关键词: Na+;    K+-ATPase;    Phosphoenzyme;    Half-site reactivity;    Oligomeric structure;    Chymotrypsin;   

DOI  :  10.1016/0014-5793(96)00687-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Purified kidney Na⁺,K⁺-ATPase whose α-subunit is cleaved by chymotrypsin at Leu²⁶⁶-Ala²⁶⁷, loses ATPase activity but forms the phosphoenzyme intermediate (EP) from ATP. When EP formation was correlated with extent of α-cleavage in the course of proteolysis, total EP increased with time before it declined. The magnitude of this rise indicated doubling of the number of phosphorylation sites after cleavage. Together with previous findings, these data establish that half of the α-subunits of oligomeric membrane-bound enzyme are dormant and that interaction of the N-terminal domain of α-subunit with its phosphorylation domain causes this half-site reactivity. Evidently, disruption of this interaction by proteolysis abolishes overall activity while it opens access to phosphorylation sites of all α-subunits.

【 授权许可】

Unknown