UBIQUINONE BIOSYNTHESIS IN EUKARYOTIC CELLS - TISSUE DISTRIBUTION OF MESSENGER-RNA ENCODING 3,4-DIHYDROXY-5-POLYPRENYLBENZOATE METHYLTRANSFERASE IN THE RAT AND MAPPING OF THE COQ3 GENE TO MOUSE CHROMOSOME-4

The isolation and sequence of a rat cDNA corresponding to the rat COQ3 gene was recently reported. The COQ3 gene encodes 3,4-dihydroxy-5-pol yprenylbenzoate methyltransferase, an enzyme in coenzyme and biosynthe sis. In this study, the rat COQ3 cDNA has been used to examine the exp ression and chromosomal localization of the COQ3 gene. COQ3 mRNA was d etected in every tissue analyzed, consistent with the idea that in mos t tissues de novo synthesis accounts for the observed levels of Q. Hig hest levels were present in testis, heart, and skeletal muscle. The ra t COQ3 cDNA hybridized to genomic DNA from multiple species, suggestin g the conserved nature of the 3,4-dihydroxy-5-polyprenylbenzoate methy ltransferase. A single copy of the COQ3 gene appears to be present in rats and mice. By analyzing a restriction fragment length variant in a n interspecific backcross, the COQ3 gene was localized to mouse chromo some 4, at a position 3.7 +/- 2.6 cM proximal to the marker D4Mit4. Th e map position of the gene, designated Coq3, places it in close proxim ity to the mouse vacillans or vc mutation. The symptoms exhibited by t he ve mice are similar to those reported for and deficiencies in human s. (C) 1994 Academic Press, Inc.