A nuclear protein(s) from rat or pig stomach recognized a conserved sequence in the 5′-upstream regions of the rat and human H+/K+-ATPase α subunit genes. A gel retardation assay suggested that part of the binding site was located in the TAATCAGCTG sequence. No nuclear proteins capable of the binding could be detected in other tissues of rat (liver, brain, kidney, spleen and lung) or pig liver. The sequence motif (GATAGC) located 5′-upstream of the β-subunit gene also seemed to be recognized by the same protein, because the binding of nuclear protein to the sequence motifs in the α and β subunits was mutually competitive. Considering the sense-strand sequence of the binding motif in the α-subunit gene, we conclude that (G/C)PuPu(G/C)NGAT(A/T)PuPy is a core sequence motif for the gastric specific DNA binding protein (PCSF, parietal cell specific factor).
