NUCLEOTIDE-SEQUENCE OF A CDNA FOR THE BETA-2 SUBUNIT ISOFORM OF NA-ATPASE FROM HUMAN RETINA(,K+)

Using as probe the entire human liver cDNA clone coding for the the be ta 2 subunit isoform of the Na+,K+-ATPase, which lacks the initiation codon ATG, and the entire 5'-untranslated region (Martin-Vasallo, P., Dackowski, W., Emanuel, J.R. and Levenson, R. (1989) J. Biol. Chem. 26 4, 4613-4618), we isolated a larger clone from a directional human adu lt retina cDNA library (Swaroop, A. and Xu, J. (1993) Cytogenet. Cell Genet. 64, 292-294). This clone, pNH beta 2, shows 100% homology with the nucleotide sequence of the human liver cDNA clone and also contain s additional 407 nucleotides in the 5'-untranslated region, the initia tion codon and a poly(A) tail. Northern blot hybridization analysis re veals that the human mRNA (3.6 kb) is approx. 300 nucleotides larger t han the major transcipt size expressed in rat (3.3 kb). The larger hum an size mRNA for the human beta 2 Na+,K+-ATPase indicates species diff erences in gene processing.