CLONING, EXPRESSION, AND MAPPING OF UBE2I, A NOVEL GENE ENCODING A HUMAN HOMOLOG OF YEAST UBIQUITIN-CONJUGATING ENZYMES WHICH ARE CRITICAL FOR REGULATING THE CELL-CYCLE

From a human fetal-brain cDNA library we isolated a novel gene sharing significant homology with two yeast genes, UBC9 and hus5, which encod e ubiquitin-conjugating enzyme 9 (UBC9). In yeast this protein is crit ical for normal mitosis, and seems to be closely involved in progressi on of G(2) to M phase of the cell cycle. The human-UBC9 (h-UBC9) cDNA, (gene symbol UBE21), contained an open reading frame of 474 nucleotid es encoding 158 amino acids. Its predicted peptide showed respectively 56% and 66% identity (75% and 82% similarity) with the products of UB C9 and hus5. Northern-blot analysis revealed expression of three trans cripts, 6.4 kb, 3.3 kb, and 1.35 kb, in all human tissues examined. Th is gene, UBE2I, was mapped to chromosome band 16p13.3 by FISH.