Assignment of a structural gene for a fourth human diaphorase (DIA4) to chromosome 16 in man-mouse somatic cell hybrids

Summary A diaphorase (DIA4), different from similar enzymes so far described in man, has been detected electrophoretically in human tissues and fibroblasts. The enzyme which is active both with NADH and NADPH was missing in erythrocytes. It was consistently undetectable in part of the diploid fibroblast cultures analyzed. The activity could be separated by Cellogel electrophoresis from rodent diaphorases. In manmouse somatic cell hybrids human DIA4 segregated with chromosome 16. This result indicates that its structural gene is located on this autosome. The enzyme exhibits similarities with a NAD(P)H dehydrogenase (EC 1.6.99.2) described in rat liver.