Serine 68 phosphorylation of phospholemman: acute isoform-specific activation of cardiac Na/K ATPase

Silverman, B. d.Z., Fuller, W. , Eaton, P., Deng, J., Moorman, J. R., Cheung, J. Y., James, A. F. and Shattock, M. J. (2005) Serine 68 phosphorylation of phospholemman: acute isoform-specific activation of cardiac Na/K ATPase. Cardiovascular Research, 65(1), pp. 93-103. (doi: 10.1016/j.cardiores.2004.09.005) (PMID:15621037)

Abstract

Objective: The mechanism by which the cardiac Na/K ATPase (NKA) is regulated by phosphorylation is controversial. We have used the perforated-patch technique to limit cell dialysis and maintain conditions as near physiological as possible. Methods: NKA pump current (Ip) was measured in isolated guinea pig ventricular myocytes, and its components (Iα1 and Iα2) defined by their differing dihydroouabain sensitivities. Results: Treatment with 1 μmol/l forskolin for 4 min at 35 °C caused a significant increase in Iα1 of 36 ± 15% (P<0.05, n=6), but no change in Iα2. The presence of the PKA selective inhibitor H89 (50 μmol/l) throughout the protocol blocked the effect of the forskolin on Iα1. Treatment with H89 alone did not change Iα1 or Iα2. Isoelectric focusing gels of the NKA α1 subunit demonstrated six charge states, which were unaltered following treatment with forskolin. Western blots using an antibody specific for the PKA phosphorylation consensus site on the α1 subunit showed no change in the phosphorylation status of this residue following forskolin treatment. The sarcolemmal protein phospholemman (PLM) was found associated with NKA α1 but not α2 subunits by immunoprecipitation and immunofluorescence. PLM was phosphorylated at serine 68, but not 63, following treatment with forskolin.

• Item Type: Articles
• Additional Information: This work was supported by grants from the British Heart Foundation, The Wellcome Trust, the NIH, the American Heart Association, and the Trustees of St. Thomas’ Hospital.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fuller, Professor Will
• Authors: Silverman, B. d.Z., Fuller, W., Eaton, P., Deng, J., Moorman, J. R., Cheung, J. Y., James, A. F., and Shattock, M. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Cardiovascular Research
• Publisher: Oxford University Press
• ISSN: 0008-6363
• ISSN (Online): 1755-3245