STRUCTURE AND TISSUE-SPECIFIC EXPRESSION OF GENES ENCODING BOVINE COPPER AMINE OXIDASES

A cDNA coding for an enzyme belonging to the family of copper amine ox idases was cloned from a bovine lung cDNA library using a PCR approach . The nucleotide sequence of this cDNA was found to be different from that of the previously published liver cDNA encoding bovine serum amin e oxidase, another copper amine oxidase. Analyses using reverse transc ription followed by PCR of RNA extracted from different bovine tissues confirmed that the copper amine oxidase gene expressed in bovine live r is closely related to, but different from, the copper amine oxidase gene expressed in bovine lung, kidney, spleen and heart. Northern blot ting data showed that the level of copper amine oxidase expression in liver is considerably higher than in the other tissues tested. Souther n blotting analyses of bovine chromosomal DNA suggested the existence of at least three copper amine oxidase genes. Two of these genes are a pparently expressed in a tissue-specific manner as outlined above. A f ragment of a third copper amine oxidase gene is identified. The exon-i ntron organization of the bovine copper amine oxidase genes analyzed i s similar to that of the related human diamine oxidase gene, except th at no intron in the position equivalent to that of the third intron in the human gene is found. In the third gene, a complete replacement of the third intron of the bovine copper amine oxidase gene (equivalent to the fourth intron of the human gene) has occurred.