HUMAN MITOCHONDRIAL CARBONIC-ANHYDRASE - CDNA CLONING, EXPRESSION, SUBCELLULAR-LOCALIZATION, AND MAPPING TO CHROMOSOME-16

A full-length cDNA clone encoding human mitochondrial carbonic anhydra se (CA), CA V, was isolated from a human liver cDNA library. The 1123- bp cDNA includes a 55-bp 5' untranslated region, a 915-bp open reading frame, and a 153-bp 3' untranslated region. Expression of the cDNA in COS cells produced active enzyme. The 34-kDa precursor and 30-kDa mat ure form of CA V were identified on Western blots of COS-cell homogena tes by a CA V-specific antibody raised to a synthetic peptide correspo nding to the C-terminal 17 aa of CA V. Both 34-kDa and 30-kDa bands we re also present in n-mitochondria isolated from transfected COS cells, whereas only the 30-kDa band was present in mitochondria isolated fro m normal human liver. The N-terminal sequence determined directly on t he 30-kDa soluble CA purified from transfected COS cells indicated tha t processing of the precursor to mature human CA V involves removal of a 38 -aa mitochondrial leader sequence. The 267-aa sequence deduced f or mature human CA V shows 30-49% similarity to amino acid sequences o f previously characterized human CAs (CA I-CA VII) and 76% similarity to the corresponding amino acid sequence deduced from the mouse cDNA. PCR analysis of DNAs from human-rodent somatic cell hybrids localized the gene for CA V to human chromosome 16, the same chromosome to which CA VII has previously been mapped.