Human Ubc9 is homologous to ubiquitin-conjugating enzymes (E2s). However, instead of conjugating ubiquitin, it conjugates a ubiquitin homologue, small ubiquitin-like modifier 1(SUMO-1). And hUbc9 retains striking structural and functional conservation with yeast Ubc9. The ubiquitin-dependent protein degradation system has been recognized as a complete enzymatic pathway that is responsible for the selective degradation of abnormal and short-lived proteins. The conjugation of ubiquitin reuires the activities of ubiquitin-activating (E1) and -conjugating (E2) enzymes. Alternative Names: EC 6.3.2 protein, UBE 2I protein, Ubiquitin conjugating enzyme UbcE2A protein, SUMO-conjugating enzyme UBC9 protein, Ubiquitin like protein SUMO 1 conjugating enzyme protein, Ubiquitin protein ligase E2I protein, Ubiquitin carrier protein 9 protein, UBCE 9 protein, SUMO1 protein ligase protein, Ubiquitin like protein SUMO1 conjugating enzyme protein, SUMO protein ligase protein, Ubiquitin protein ligase I protein, Human ubiquitin conjugating enzyme 9 protein, UBC9 homolog protein, p18 protein, SUMO 1 conjugating enzyme protein, , Ubiquitin conjugating enzyme E2I protein, UBCE9 protein, SUMO 1 protein ligase protein, Ubiquitin-conjugating enzyme E2I C358B7.1 protein, Ubiquitin-protein ligase I protein, UBC 9 protein, Ubiquitin carrier protein I protein, Ubiquitin carrier protein protein, SUMO1 conjugating enzyme protein, Ubiquitin conjugating enzyme 9 protein, p18 protein, Homologous to yeast UBC9 protein, UBE2I protein, Ubc9 protein, UBC9 protein, SUMO-protein ligase protein, SUMO conjugating enzyme UBC9 protein, Ubiquitin-conjugating enzyme E2 I protein