title: p104 binds to Rac1 and reduces its activity during myotube differentiation of C2C12 cell.
abstract: The p104 protein inhibits cellular proliferation when overexpressed in NIH3T3 cells and has been shown to associate with p85α, Grb2, and PLCγ1. In order to isolate other proteins that interact with p104, yeast two-hybrid screening was performed. Rac1 was identified as a binding partner of p104 and the interaction between p104 and Rac1 was confirmed by immunoprecipitation. Using a glutathione S-transferase (GST) pull-down assay with various p104 fragments, the 814-848 amino acid residue at the carboxyl-terminal region of p104 was identified as the key component to interact with Rac1. The CrkII which is involved in the Rac1-mediated cellular response was also found to interact with p104 protein. NIH3T3 cells which overexpressed p104 showed a decrease of Rac1 activity. However, neither the proline-rich domain mutant, which is unable to interact with CrkII, nor the carboxy-terminal deletion mutant could attenuate Rac1 activity. During the differentiation of myoblasts, the amount of p104 protein as well as transcript level was increased. The overexpression of p104 enhanced myotube differentiation, whereas siRNA of p104 reversed this process. In this process, more Rac1 and CrkII were bound to increased p104. Based on these results, we conclude that p104 is involved in muscle cell differentiation by modulating the Rac1 activity.
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Republic of Korea ; School of Biological Sciences, Seoul National University, San 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Ki Young
authors.identifier: 0000-0003-2799-5274
authors.initials: KY
authors.lastname: Choi
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Republic of Korea ; School of Biological Sciences, Seoul National University, San 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Min Sup
authors.initials: MS
authors.lastname: Lee
authors.affiliation: School of Biological Sciences, Seoul National University, San 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Cho
authors.affiliation: School of Biological Sciences, Inje University, Gimhae 621-749, Republic of Korea.
authors.forename: Myong Ho
authors.initials: MH
authors.lastname: Jeong
authors.affiliation: School of Biological Sciences, Inje University, Gimhae 621-749, Republic of Korea.
authors.forename: Seung Jin
authors.identifier: 0000-0003-3574-7668
authors.initials: SJ
authors.lastname: Han
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Republic of Korea ; School of Biological Sciences, Seoul National University, San 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Seung Hwan
authors.identifier: 0000-0001-6344-669X
authors.initials: SH
authors.lastname: Hong
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D017353:Gene Deletion; D051379:Mice; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D041681:NIH 3T3 Cells; D009479:Neuropeptides / Q000378:metabolism*; D011485:Protein Binding; D050737:Proto-Oncogene Proteins c-crk / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D009479:Neuropeptides; D050737:Proto-Oncogene Proteins c-crk; D012333:RNA, Messenger; C484602:Rac1 protein, mouse; C550625:p104 protein, mouse; D020830:rac1 GTP-Binding Protein