Vascular smooth muscle expresses a truncated Na+, K(+)-ATPase alpha-1 subunit isoform.
By regulating transmembrane Na+ and K+ concentrations and membrane potential, the Na+,K(+)-ATPase plays an important role in regulating cardiac, skeletal, and smooth muscle function. A high degree of amino acid sequence and structural identity characterizes the three Mr 100,000 Na+,K(+)-ATPase alpha subunit isoforms expressed in cardiac and skeletal muscle. Strikingly, vascular smooth muscle utilizes alternative RNA processing of the alpha-1 gene to express a structurally distinct Mr approximately 65,000 isoform, alpha 1-T (truncated). Analysis of both its mRNA and protein structure reveals that alpha-1-T represents a major, evolutionarily conserved, truncated Na+,K(+)-ATPase isoform expressed in vascular smooth muscle. This demonstrates an unexpected complexity in the regulation of vascular smooth muscle Na+,K(+)-ATPase gene expression and suggests that a structurally novel, truncated alpha subunit may play a role in vascular smooth muscle active ion transport.
Medford
R M
RM
Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322.
Hyman
R
R
Ahmad
M
M
Allen
J C
JC
Pressley
T A
TA
Allen
P D
PD
Nadal-Ginard
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002462:Cell Membrane / Q000201:enzymology; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000235:genetics*; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000502:physiology; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*
D007527:Isoenzymes; D012333:RNA, Messenger; D004247:DNA; D000254:Sodium-Potassium-Exchanging ATPase