Are there several isoforms of Na,K-ATPase alpha subunit in the rabbit kidney?
Previous pharmacologic and kinetic studies have demonstrated the axial heterogeneity of the rabbit kidney tubule with regard to Na,K-ATPase. To evaluate whether this heterogeneity might reflect the presence of distinct isoforms of the alpha subunit of Na,K-ATPase, we used two monoclonal antibodies, IIC9 and IIE2 (G8), specific for the alpha 1 and alpha 3 isoforms, respectively, as probes for changes in the specific activity of Na,K-ATPase at the level of successive segments of the rabbit nephron. Single, well defined nephron segments were obtained by microdissection of collagenase-treated kidney. Results indicate that IIC9 antibody inhibited Na,K-ATPase activity by > 90% in all the segments of the nephron except the collecting duct. Conversely, IIE2 (G8) antibody abolished Na,K-ATPase activity in the collecting duct, whereas it had no effect in other nephron segments. These findings suggest that the rabbit collecting duct preferentially expresses a distinct isoform of Na,K-ATPase catalytic subunit, which is presumably alpha 3-like, in agreement with previous pharmacologic and kinetic observations, whereas other nephron segments would express the alpha 1 isoform.
Laboratoire de Physiologie Cellulaire, Centre National de la Recherche Scientifique, Unité Recherche associée 219.
C
C
Barlet-Bas
E
E
Arystarkhova
L
L
Cheval
S
S
Marsy
K
K
Sweadner
N
N
Modyanov
A
A
Doucet
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001666:Binding Sites, Antibody; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007684:Kidney Tubules / Q000201:enzymology*; D046911:Macromolecular Substances; D008297:Male; D008969:Molecular Sequence Data; D009399:Nephrons / Q000201:enzymology*; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D046911:Macromolecular Substances; D000254:Sodium-Potassium-Exchanging ATPase