The function of ENSG00000103275 (UBE2I, ubiquitin conjugating enzyme E2 I) is as follows. Accepts the ubiquitin-like proteins SUMO1, SUMO2, SUMO3, SUMO4 and SUMO1P1/SUMO5 from the UBLE1A-UBLE1B E1 complex and catalyzes their covalent attachment to other proteins with the help of an E3 ligase such as RANBP2, CBX4 and ZNF451. Can catalyze the formation of poly-SUMO chains. Necessary for sumoylation of FOXL2 and KAT5. Essential for nuclear architecture and chromosome segregation. Sumoylates p53/TP53 at 'Lys-386'. Mediates sumoylation of ERCC6 which is essential for its transcription-coupled nucleotide excision repair activity (PubMed:26620705). Sumoylates SHMT1 at 'Lys-38' or 'Lys-39' leading to RAN-dependent nuclear import of SHMT1 (PubMed:17446168). Also sumoylates TYMS and DHFR (PubMed:18067453). {ECO:0000269|PubMed:11451954, ECO:0000269|PubMed:15809060, ECO:0000269|PubMed:17446168, ECO:0000269|PubMed:17466333, ECO:0000269|PubMed:18067453, ECO:0000269|PubMed:19638400, ECO:0000269|PubMed:19744555, ECO:0000269|PubMed:20077568, ECO:0000269|PubMed:26524494, ECO:0000269|PubMed:26620705, ECO:0000269|PubMed:27211601, ECO:0000269|PubMed:8668529}.