MOLECULAR-CLONING OF THE CDNA AND CHROMOSOME LOCALIZATION OF THE GENEFOR HUMAN UBIQUITIN-CONJUGATING ENZYME-9

We report a novel human gene whose product specifically associates wit h the negative regulatory domain of the Wilms' tumor gene product (WT1 ) in a yeast two-hybrid screen and with WT1 in immunoprecipitation and glutathione S-transferase (GST) capture assays. The gene encodes a 17 -kDa protein that has 56% amino acid sequence identity with yeast ubiq uitin-conjugating enzyme (yUBC) 9, a protein required for cell cycle p rogression in yeast, and significant identity with other subfamilies o f ubiquitin-conjugating enzymes. The human gene fully complements yeas t that have a temperature-sensitive yUBC9 gene mutation to fully resto re normal growth, indicating that we have cloned a functionally conser ved human (h) homolog of yUBC9. Transcripts of hUBC9 of 4.4 kilobases (kb), 2.8 kb, and 1.3 kb were found in all human tissues tested. A sin gle copy of the hUBC9 gene was found and localized to human chromosome 16p13.3. We conclude that hUBC9 retains striking structural and funct ional conservation with yUBC9 and suggest a possible link of the ubiqu itin/proteosome proteolytic pathway and the WT1 transcriptional repres sor system.