Isolation, Characterization, and Mapping of Human and Mouse Carbonic Anhydrase II Genes.

Carbonic anhydrase (E.C. 4.2.1.1., carbonate dehydratase) catalyzes the reversible hydration of CO(,2). There are at least three isozymes (designated CA I, CA II, and CA III) present in amniotes (mammals, birds, and reptiles), each coded by a separate locus. In humans, a deficiency of CA II causes a syndrome of osteopetrosis with renal tubular acidosis and cerebral calcification. The CA I and CA II genes have been shown to be linked in several mammalian species including a primate (Macaca nemestrina), and in the mouse these genes are located near the centromere of chromosome 3. Using a mouse CA II cDNA clone (pMCAII) and a panel of 28 human-rodent somatic cell hybrids, the human CA II gene (CA2) has been mapped to chromosome 8 near the gene for glutathione reductase (GSR). This finding provides the second polymorphic marker for human chromosome 8 and , moreover, a new molecular disease marker. Cosmid and lambda libraries (mouse strain YBR) were screened with pMCAII insert DNA. Two positive cosmid (A6 and 54) and four positive lambda (8.1, 8.2, 9.1, and 15.1) clones were characterized extensively. Together, the six clones encompass the entire CA II gene, 12 kb of 5' flanking region and 33 kb of 3' flanking region. Cosmid A6 contains the entire CA II gene. From restriction endonuclease analysis it was found that the gene is 16 kb in length and is coded by at least five exons. One intron is over five kb in length. A human genomic library was screened for CA II sequences. Six positive clones were purified and three (10, 11, and 25) were extensively analyzed. Clone 25 contains the nucleotides coding for amino acid residues 58 to 77 of CA II, as shown by DNA sequence analysis, and probably more. A donor sequence for splicing was found which agrees well with the consensus donor sequence. The other two clones (10 and 11) contain sequences 3' to those of clone 25 based on hybridization to subfragments of pMCAII.Ph.D.GeneticsUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159851/1/8402396.pd