FLUORESCENCE IN-SITU HYBRIDIZATION MAPPING OF THE ALPHA-SUBUNIT AND BETA-SUBUNIT (HADHA AND HADHB) OF HUMAN MITOCHONDRIAL FATTY-ACID BETA-OXIDATION MULTIENZYME COMPLEX TO 2P23 AND THEIR EVOLUTION

Mitochondrial fatty acid beta-oxidation multienzyme complex/trifunctio nal protein has an alpha 4 beta 4 structure and catalyzes the second t hrough fourth reactions of the fatty acid beta-oxidation cycle. The al pha and beta subunits (HADHA and HADHB) are members of the enoyl-CoA h ydratase/3-hydroxyacyl-CoA dehydrogenase and 3-ketoacyl-CoA thiolase f amilies, respectively. We analyzed the localization of each of these t wo genes (HADHA and HADHB) by in situ hybridization and found that bot h can be assigned to human chromosome band 2p23. Since the distance be tween the two loci is quite short, the two genes seem to exist side by side, as do the two (A and B subunit) genes of the bacterial fatty ac id beta-oxidation multienzyme complex. This is an important and intere sting finding in that two entirely different genes, encoding two indep endent proteins forming a multienzyme complex, are adjacent on chromos ome band 2p23.