Dephosphorylation of the guanylyl cyclase-A receptor causes desensitization.
Atrial natriuretic peptide (ANP) binds to the guanylyl cyclase-A (GC-A) receptor found in tissues such as the kidney and adrenal gland, resulting in marked elevations of the intracellular signaling molecule, cGMP. Here, GC-A is shown to exist as a phosphoprotein when expressed in human embryonic 293 cells. The 32P is principally associated with phosphoserine, with only trace amounts of phosphothreonine. The addition of ANP causes a time-dependent dephosphorylation of the receptor, as well as desensitization, which is not due to an ANP-mediated decrease in the amount of receptor protein. The mobility of GC-A on sodium dodecyl sulfate-polyacrylamide gel electrophoresis increases after treatment of cells with ANP, and protein phosphatase 2A induces the same mobility shift. The protein phosphatase also catalyzes dephosphorylation of GC-A, and this is directly correlated with decreases in ANP-stimulatable guanylyl cyclase activity. Okadaic acid, an inhibitor of protein phosphatase 2A, blocks both the dephosphorylation and the desensitization. Therefore, in contrast to many other cell surface receptors, GC-A is desensitized by ligand-induced dephosphorylation.
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232.
L R
LR
Potter
D L
DL
Garbers
D000595:Amino Acid Sequence; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D002384:Catalysis; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006162:Guanylate Cyclase / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D054648:Protein Phosphatase 2; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism*
D010750:Phosphoproteins; D011956:Receptors, Cell Surface; D009320:Atrial Natriuretic Factor; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A