[Gastric proton pump: genes and their expression].
The gastric proton pump (H+/K(+)-ATPase) is a typical P-type ATPase consisting of the alpha and beta subunits and secreting acid into stomach. This enzyme is similar to Na+/K(+)-ATPase in primary structure and gene organization. The exon/intron organizations of the genes for the two subunits of H+/K(+)-ATPase are highly similar to those of the corresponding subunits of Na+/K(+)-ATPase. In contrast to Na+/K(+)-ATPase subunits, alpha and beta subunits of H+/K(+)-ATPase are expressed specifically in gastric parietal cells. Consistently, a sequence motif [(G/C)PuPu(G/C)NGAT(A/T)PuPy] in the 5'upstream regions of the H+/K(+)-ATPase subunit genes was recognized by the gastric mucosal nuclear protein(s). We found that two novel zinc-finger proteins (GATA-GT1 and GATA-GT2) are present in the gastric parietal cells and bind to this motif. These proteins activate the transcription of the reporter gene connected with the 5'-upstream regions of the H+/K(+)-ATPase subunit genes. These results suggest that gastric GATA-DNA binding proteins have roles in activating transcription of H+/K(+)-ATPase genes in parietal cells.
Futai
M
M
Division of Biological Science, ISIR, Osaka University.
D000818:Animals; D004268:DNA-Binding Proteins / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D017506:H(+)-K(+)-Exchanging ATPase / Q000235:genetics*; D006801:Humans; D011485:Protein Binding / Q000502:physiology; D017494:Proton Pumps; D013270:Stomach / Q000201:enzymology; D014158:Transcription, Genetic; D016335:Zinc Fingers / Q000502:physiology
D004268:DNA-Binding Proteins; D017494:Proton Pumps; D017506:H(+)-K(+)-Exchanging ATPase