Premium
Angiotensin II (Ang II) Alters the Interaction of Na,K‐ATPase with the Cardiac Glycoside Digoxin via Multiple Sites of Phosphorylation on the α‐subunit
Author(s) -
Yingst Douglas R.,
Doci Tabitha M.,
Li Quanwen,
Rossi Noreen F.,
Massey Katherine J.,
Mattingly Raymond R.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a534-a
Subject(s) - digoxin , phosphorylation , ouabain , chemistry , protein subunit , cardiac glycoside , angiotensin ii , atpase , gi alpha subunit , microbiology and biotechnology , biochemistry , receptor , biology , medicine , enzyme , sodium , heart failure , organic chemistry , gene
To test how Ang II alters the interaction of Na,K‐ATPase with cardiac glycosides we mutated specific sites of phosphorylation on the rat α‐1 subunit of Na,K‐ATPase to residues that cannot be phosphorylated and stably co‐expressed each with the AT 1a receptor in opossum kidney cells. Cells were treated ± 10 nM Ang II and lysed in a hypotonic solution. Protein was bound to a digoxin‐affinity column in the presence of ligands that promote the E 2 ‐P conformation of Na,K‐ATPase and eluted by ligands that trigger the decay of E 2 ‐P. Ang II changed the elution profile of protein from cells expressing the wild‐type rat α‐1 subunit, but had no effect on the elution of protein from cells expressing α‐1.Y10F. Ang II also modified the elution of protein from cells expressing α‐1.S943A and from cells expressing the α‐1.S16A/S23A double mutant, but in different patterns than observed in cells expressing wild type rat α‐1 subunit. Thus, the ability of Ang II to alter the interaction of the Na,K‐ATPase with digoxin requires phosphorylation of Tyr‐10, whereas phosphorylation of Ser‐943 and Ser‐16/Ser‐23 modulate the interaction. Finally, these results implicate Tyr‐10 and Ser‐943 in how Ang II affects the Na,K‐ATPase, suggest that Ang II alters the kinetic properties of Na,K‐ATPase, and show that Ang II might regulate Na,K‐ATPase activity by changing its interaction with cardiac glycosides. Supported by NIH DK60752.