Identification of a putative isoform of the Na,K-ATPase beta subunit. Primary structure and tissue-specific expression.
We have isolated cDNA clones from rat brain and human liver encoding a putative isoform of the Na,K-ATPase beta subunit. The rat brain cDNA contains an open reading frame of 870 nucleotides coding for a protein of 290 amino acids with a calculated molecular weight of 33,412. The corresponding amino acid sequence shows 98% identity with its human liver counterpart. The proteins encoded by the rat and human cDNAs exhibit a high degree of primary sequence and secondary structure similarity with the rat Na,K-ATPase beta subunit. We have therefore termed the polypeptides these cDNAs encode a beta 2 subunit with the previously characterized rat cDNA encoding a beta 1 subunit. Analysis of rat tissue RNA reveals that the beta 2 subunit gene encodes a 3.4-kilobase mRNA which is expressed in a tissue specific fashion distinct from that of rat beta 1 subunit mRNA. Cell lines derived from the rat central nervous system shown to lack beta 1 subunit mRNA sequences were found to express beta 2 subunit mRNA. These results suggest that different members of the Na,K-ATPase beta subunit family may have specialized functions.
Martin-Vasallo
P
P
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Dackowski
W
W
Emanuel
J R
JR
Levenson
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D006031:Glycosylation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008099:Liver / Q000032:analysis; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D011487:Protein Conformation; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*; D014018:Tissue Distribution; D014158:Transcription, Genetic
D007527:Isoenzymes; D012333:RNA, Messenger; D004247:DNA; D000254:Sodium-Potassium-Exchanging ATPase