| Interaction of the developmental regulator SALL 1 with UBE2I and SUMO 1 . ^^^ Here , we show that the ubiquitin conjugating enzyme 2I ( UBE2I ) , the human homolog of S . cerevisiae UBC 9 , and the small ubiquitin like modifier 1 ( SUMO 1 ) interact with SALL 1 in the yeast two hybrid system . ^^^ In an in vitro assay , it could be demonstrated that SALL 1 is covalently modified by at least two SUMO 1 molecules in the presence of UBA2 / AOS1 and UBE2I . ^^^ Mutation of lysine 1086 of SALL 1 to arginine abrogates SALL 1 sumoylation , suggesting the presence of a polymeric SUMO 1 chain in the wild type state . . ^^^ |