The SUMO1 Modification Of FAM122A And Its Biological Function

FAM122A protein is one of the proteins that were found by proteomic technology,which interacts with the family proteins of the f-box(Skp1/Cul1/ f-box protein complex).Early report shows that FAM122 A induce PP2A-C? degradation by poly-ubiquitin/proteasome system and reduce the phosphatase activity of PP2 A.Thus,FAM122 A is a novel endogenous inhibitor of PP2 A.Our present study shows that FAM122 A is modified by SUMO1(SUMO Small Ubiquitin-like Modifier)and the sumoylation is desumoylated by SENP1.Next,we predict the SUMO1 modification site is lysine 89 by SUMOplot(tm)analyses program online.It strongly suggests the lysine 89 of FAM122 A may be the main site of SUMO1 modification.As expected,we confirm that the lysine 89 is indeed the site of SUMO1 modification of FAM122 A by IP experiment.Moreover,we find the SUMO1 modification of FAM122 A can decrease PP2A-C? protein level further by the poly-ubiquitin/proteasome system,accompanied by the activity of PP2 A phosphatase decreased and cell proliferation was suppressed.On the other hand,we find that the SUMO1 modification of FAM122 A impact the interaction of proteins through IP-MS(immunoprecipited-mass spectrum analysis).In summary,we find that FAM122 A can be modified by SUMO1 and the SUMO1 modification is novel regulator of FAM122 A.