Structure and expression of the human Na,K-ATPase beta 2-subunit gene.

We cloned and characterized the human Na,K-ATPase beta 2-subunit gene. The gene encompasses over 8 kb at chromosome 17 in the human genome and is composed of seven exons. Primer extension analysis identified a major transcription initiation site 529 bases upstream of the translation start site. The 5'-flanking region of the gene harbors a potential TATA sequence, located 94 bases upstream of the transcription initiation site and a number of potential promoter and regulatory elements, among them a Sp1 site, at position -120. A functional Sp1 site has also been found in the rat Na,K-ATPase beta 2-subunit gene (Kawakami, K., Watanabe, Y., Araki, M., Nagano, K., 1993). Sp1 binds to the adhesion molecule on glia regulatory element that functions as a positive transcription regulatory element in astrocytes. (J. Neurosci. Res. 35, 138-146). Putative AATAAA and TG sequences were found at positions 7018 and 7068, respectively. These signals delimit the origin of the the poly(A) tail and mark the end of the sequence that completes the 3'-UT downstream sequence of the human cDNA. An Alu repetitive sequence is located between positions 5961 and 6274. The gene is expressed as a single mRNA species, of 3.36 kb, which is present in cerebrum, cerebellum, kidney and heart, being more abundant in neural tissues. Structural analyses of this and other of the P-type ATPase beta subunit genes reveal that they evolved from a common ancestor.