Tissue specific membrane association of alpha 1T, a truncated form of the alpha 1 subunit of the Na pump.
We have assessed the Na pump alpha-subunit isoform content utilizing site directed antibodies in two vascular smooth muscle (VSM) preparations known to contain functional Na pump sites, VSM microsomal fractions (Na+, K(+)-ATPase) and intact primary confluent cells (ouabain inhibited 86Rb uptake). A comparison of isoform content was made with kidney microsomes. Both VSM and kidney microsomes contained a full length alpha 1 subunit (approximately 100 kDa) as well as a truncated subunit, alpha 1T (approximately 66 kDa). SDS treatment of VSM microsomes effected an increase in Na+, K(+)-ATPase and a retention of alpha 1T. SDS treated kidney microsomes retained the alpha 1 isoform and Na+, K(+)-ATPase. Confluent VSM cells showed no detectable alpha 1, only alpha 1T. In the absence of detectable full length alpha 1, the alpha 1T protein may represent a functional Na pump component in canine VSM.
Allen
J C
JC
Department of Medicine, Baylor College of Medicine, Houston, TX 77030-3498.
Pressley
T A
TA
Odebunmi
T
T
Medford
R M
RM
D000818:Animals; D002339:Carotid Arteries; D002478:Cells, Cultured; D004285:Dogs; D007668:Kidney / Q000201:enzymology / Q000648:ultrastructure; D008861:Microsomes / Q000201:enzymology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000648:ultrastructure; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology; D012414:Rubidium Radioisotopes; D012501:Saphenous Vein; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014018:Tissue Distribution
D012414:Rubidium Radioisotopes; D012967:Sodium Dodecyl Sulfate; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase