Phosphorylation of S955 at the protein kinase A consensus promotes maturation of the alpha subunit of the colonic H+,K+ -ATPase.
All the alpha subunits of the Na+,K+ -ATPases and H+,K+ -ATPases have a protein kinase A (PKA) consensus sequence near or in the ninth transmembrane domain. The role of this domain in influencing alpha subunit synthesis/degradation, plasma membrane localization, and 86Rb+ uptake has not been established for the alpha subunit of the colonic H+,K+ -ATPase. This study examined the effect of mutating S955 (within the PKA consensus site of the alpha subunit of the colonic H+,K+ -ATPase [HKalpha2]) to alanine (S955/A) or aspartic acid (S955/D) on alpha subunit expression and function. The results demonstrate that a negatively charged amino acid at position 955 of HKalpha2 promotes higher expression levels of both whole-cell and plasma membrane-localized HKalpha2. Moreover, inhibition of PKA reduced expression of wild-type HKalpha2 and associated 86Rb+ uptake. Last, the activity of the HKalpha2 S955/A was rescued by treatment with 4-phenylbutyric acid, a compound that was shown previously to restore function to the cystic fibrosis transmembrane conductance regulator.
Codina
Juan
J
Sections on Nephrology and Molecular Medicine, Department of Internal Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
Liu
Jingfang
J
Bleyer
Anthony J
AJ
Penn
Raymond B
RB
DuBose
Thomas D
TD
D000409:Alanine / Q000235:genetics; D019921:Biotinylation; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003106:Colon / Q000378:metabolism; D016384:Consensus Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017506:H(+)-K(+)-Exchanging ATPase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D021122:Protein Subunits / Q000378:metabolism; D012414:Rubidium Radioisotopes / Q000493:pharmacokinetics; D014162:Transfection
D021122:Protein Subunits; D012414:Rubidium Radioisotopes; D017868:Cyclic AMP-Dependent Protein Kinases; D017506:H(+)-K(+)-Exchanging ATPase; D000409:Alanine