Characterization of the phosphorylation state of natriuretic peptide receptor-C.
Many internalized receptors are known to be phosphorylated within their cytoplasmic domain. Natriuretic peptide receptor-C (NPR-C) is a covalent homodimer primarily involved in the internalization of bound ligand resulting in tissue uptake and degradation of natriuretic peptides. In this report, we have investigated the phosphorylation state of NPR-C receptors present at high level in rat aortic smooth muscle cells (RASM). 32P labeled cells, NPR-C purification and phosphoamino acid analysis clearly demonstrate that NPR-C exists as a phosphoprotein in RASM cells and that phosphorylation occurs exclusively on serine residues. Transient expression of bovine NPR-C in Cos-P cells of kidney origin confirmed that phosphorylation occurs within the cytoplasmic domain of the receptor. These results provide the first evidence for NPR-C phosphorylation as well as a model for future studies of its role in altering receptor function.
Pedro
L
L
Département de Pharmacologie, Université de Montréal, Québec, Canada.
Fenrick
R
R
Marquis
M
M
McNicoll
N
N
De Léan
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001667:Binding, Competitive; D002417:Cattle; D002478:Cells, Cultured; D006162:Guanylate Cyclase / Q000378:metabolism*; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*
D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C