BACKGROUND: A major pathway for protein degradation in eukaryocytes is ubiquitin-dependent. A novel species of plant and mammalian E2 homologous to yeast UBC4/UBC5 is involved in polyubiquitination and degradation of off and many other proteins as well. METHODS: By sequencing the Expressed Sequence Taqs(ESTs) of human dermal papilla cDNA library, we isolated a clone, named K183 which showed high homology to the yeast UBC4/UBC5. We designated this gene as UBC-dp. RESULTS: K183 clone is 1,222 nucleotides long, and has a coding region of 622 nucleotides and a 3' noncoding region of 538 nucleotides. The presumed open reading frame starting at the 5' terminus of UBC-dp encodes 207 amino acids. The amino acid sequence deduced from the open reading frame of UBC-dp shares 81%, 80% and 80% identities with that of HSUBCH5. yeast UBC4 and yeast UBC5, respectively. The transcripts were ubiquitously expressed in a variety of human tissues. The levels of transcript were relatively high in those tissues such as skeletal muscle, heart, testis and ovary. CONCLUSIONS: Homology search result suggests that K183 clone is human homolog of the UBC4 and UBC5 which are involved in p53 degradation so its function related with p53 should be studied.