Structure/function analysis of Na(+)-K(+)-ATPase central isoform-specific region: involvement in PKC regulation.
Specific functions served by the various Na(+)-K(+)-ATPase alpha-isoforms are likely to originate in regions of structural divergence within their primary structures. The isoforms are nearly identical, with the exception of the NH(2) terminus and a 10-residue region near the center of each molecule (isoform-specific region; ISR). Although the NH(2) terminus has been clearly identified as a source of isoform functional diversity, other regions seem to be involved. We investigated whether the central ISR could also contribute to isoform variability. We constructed chimeric molecules in which the central ISRs of rat alpha(1)- and alpha(2)-isoforms were exchanged. After stable transfection into opossum kidney cells, the chimeras were characterized for two properties known to differ dramatically among the isoforms: their K(+) deocclusion pattern and their response to PKC activation. Comparisons with rat full-length alpha(1)- and alpha(2)-isoforms expressed under the same conditions suggest an involvement of the central ISR in the response to PKC but not in K(+) deocclusion.
Pierre
Sandrine V
SV
Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA. Sandrine.Pierre@ttuhsc.edu
Duran
Marie-Josée
MJ
Carr
Deborah L
DL
Pressley
Thomas A
TA
D000595:Amino Acid Sequence; D000818:Animals; D015971:Gene Expression Regulation, Enzymologic; D007536:Isomerism; D007668:Kidney / Q000201:enzymology*; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins; D012413:Rubidium / Q000493:pharmacokinetics; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013329:Structure-Activity Relationship
D011993:Recombinant Fusion Proteins; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D011188:Potassium