CLONING OF A NOVEL CDNA HOMOLOGOUS TO CHIP28 WATER CHANNEL FROM OCULAR CILIARY EPITHELIUM

Water channel protein (CHIP28) has been initially identified from huma n erythrocyte and subsequently localized in human kidney, rat kidney a nd bovine corneal endothelium. We report here cloning of homologous cD NA (CHIP29) from an expression cDNA library constructed from bovine ci liary epithelium poly A(+) that codes a 271 amino acid, 28.8 kDa prote in. At the amino acid level, bovine CHIP29 is 91% identical to the CHI P28 protein. Analysis of the deduced amino acid sequence indicated a h ydrophobic protein with six membrane spanning domains, one N-linked gl ycosylation site, two consented NPA boxes common to MIP26 family prote ins, and conserved amino acid residue cysteine 189 common to water cha nnels. Northern blotting revealed a major mRNA of 2.8 Kb size expresse d in bovine ciliary epithelium. The results presented here confirm the presence of water channel gene in the bovine ciliary epithelium, a pr imary site for the aqueous humor production. (C) 1994 Academic Press, Inc.