Question: Which enzyme is crucial for protein function regulation and tumorigenesis by interacting with partners needed for sumoylation in the pathway?

Context:
oylation and plays a central role by interacting with almost all of the partners required for sumoylation", "Here we demonstrate that the synaptic diffusion of Ubc9, the sole conjugating enzyme of the sumoylation pathway, is regulated by synaptic activity", "Here, we investigated inhibition of sumoylation as a novel antifibrotic approach.Sumoylation was inhibited by siRNA-mediated knockdown of the Small Ubiquitin-like MOdifiers (SUMO) E2-conjugating enzyme Ubc9, which is essential for sumoylation", "Here we have identified host cell proteins involved with the cellular SUMOylation pathway, SUMO-1 (small ubiquitin-like modifier) and UBC9, a SUMO-1 conjugating enzyme that interact with classical swine fever virus (CSFV) Core protein", "A new pathway that contributes to mutant CFTR degradation is mediated by the small heat shock protein, Hsp27, which cooperates with Ubc9, the E2 enzyme for SUMOylation, to selectively conjugate mutant CFTR with SUMO-2/3", "Using transfection of Ets-1 wildtype (WT) or its sumoylation deficient version (Ets-1 K15R/K227R), as well as WT or mutant proteins of the SUMO pathway, we further demonstrated that the E2 SUMO-conjugating enzyme Ubc9 and a E3 SUMO ligase, PIASy, can enhance Ets-1 sumoylation, while a SUMO protease, SENP1, can desumoylate Ets-1", "The results show that basal SUMO modification is required for stimuli-induced p100 phosphorylation and that blocking SUMOylation of p100, either by site-directed mutation or by short interfering RNA-targeted diminution of E2 SUMO-conjugating enzyme Ubc9, inhibits various physiological stimuli-induced p100 processing and ultimate activation of the alternative NF-kappaB pathway", "Sumoylation proceeds via an enzymatic pathway that is mechanistically analogous to ubiquitination, but requires a different E1-activating enzyme and Ubc9, a SUMO-specific E2-conjugating enzyme", "SUMO-conjugating enzyme E2 UBC9 mediates viral immediate-early protein SUMOylation in crayfish to facilitate reproduction of white spot syndrome virus.", "OBJECTIVE: To determine the role of ubiquitin-conjugating enzyme 9 (UBC9), a small ubiquitin-like modifier-conjugating enzyme, in cardiomyocyte protein quality control. ", "Ubiquitin-conjugating enzyme             9 (Ubc9), the sole conjugating enzyme for sumoylation, regulates protein function             and plays a key role in tumorigenesis. ", "UBC9 is the only E2 conjugating enzyme involved in this process, and loss of UBC9 completely abolishes the SUMOylation pathway.", "Here we demonstrate that the synaptic diffusion of Ubc9, the sole conjugating enzyme of the sumoylation pathway, is regulated by synaptic activity.", "Sumoylation proceeds via an enzymatic pathway that is mechanistically analogous to ubiquitination, but requires a different E1-activating enzyme and Ubc9, a SUMO-specific E2-conjugating enzyme.", "Western blot analysis, EMSA, ELISA, confocal microscopy and immunoprecipitation demonstrated that drastic tissue hypoxia, elevated levels of proteins conjugated by small ubiquitin-related modifier-1 (SUMO-1), Ubc9 (the only known conjugating enzyme for the sumoylation pathway) or HIF-1\u03b1, augmented sumoylation of HIF-1\u03b1, nucleus-bound translocation and enhanced transcriptional activity of HIF-1\u03b1 in RVLM neurons took place preferentially during the pro-life phase of experimental brain death.", "In this study, we found that the SUMOylation pathway was involved in the DENV life cycle, since DENV replication was reduced by silencing the cellular gene Ubc9, which encodes the sole E2-conjugating enzyme required for SUMOylation.", "In this study, we revisited the role of Tax SUMOylation using a strategy based on the targeting of Ubc9, the unique E2 SUMO-conjugating enzyme.", "Taken together, these findings provide evidence for regulated sumoylation as a mechanism to modulate the activity of Tec1 and validate Ubc9 fusion-directed sumoylation as a useful approach for studying

Answer: Ubiquitin-conjugating enzyme 9 (Ubc9)