CLONING AND CHROMOSOME MAPPING OF THE HUMAN MEL-18 GENE WHICH ENCODESA DNA-BINDING PROTEIN WITH A NEW RING-FINGER MOTIF

It has recently been reported that there exists a new 'RING-finger' pr otein family among the zinc-finger (Zf) proteins. Previously, we had i solated the mouse Mel-18 cDNA (mMel-18) encoding the nuclear RING-fing er protein that exhibits an ability to bind to a nonspecific DNA colum n. Here, we have isolated and characterized the human Mel-18 cDNA (hMe l-18) using the mMel-18 cDNA as a probe. The deduced hMel-18 protein c ontains 344 amino acids (38 kDa) with a RING-finger motif, a helix-loo p-helix (HLH)-like structure and a Pro/Ser-rich region. The hMel-18 ge ne is conserved among vertebrates. Its mRNA is highly expressed in pla centa, lung and kidney, but the level is low in liver, pancreas and sk eletal muscle. Using in situ hybridization, we mapped hMel-18 to band q22 of chromosome 12. It is possible that the Mel-18/bmi-1 gene family represents a mammalian homologue of the Drosophila polycomb gene grou p.