title: Sumoylation of heterogeneous nuclear ribonucleoproteins, zinc finger proteins, and nuclear pore complex proteins: a proteomic analysis.
abstract: SUMO, a small ubiquitin-related modifier, is known to covalently attach to a number of nuclear regulatory proteins such as p53, IkappaB, promyelocytic leukemia protein and c-Jun. The sumoylation reaction is catalyzed by the SUMO protease, which exposes the C-terminal active glycine residue of the nascent SUMO, the heterodimeric SUMO activating enzyme, the SUMO conjugating enzyme, Ubc9, and SUMO protein ligases, in a manner similar to ubiquitinylation. Identification of SUMO-regulated proteins is hampered by the fact that many sumoylated proteins are present at a level below normal detection limit. This limitation was overcome by either in vivo overexpression of Myc-SUMO or in vitro sumoylation with excess biotin-SUMO and Ubc9. Sumoylated proteins so obtained were affinity purified or isolated by immunoprecipitation. The isolated sumoylated proteins were identified by sequence analysis using mass spectrometric methods. Results reveal that several heterogeneous nuclear ribonucleoproteins (hnRNPs), zinc finger proteins, and nuclear pore complex proteins were sumoylated. The sumoylation of hnRNP A1, hnRNP F, and hnRNP K were confirmed in vivo by coimmunoprecipitation. In view of the facts that hnRNPs have been implicated in RNA splicing, transport, stability, and translation, our findings suggest that sumoylation could play an important role in regulating mRNA metabolism.
authors.affiliation: Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-8012, USA.
authors.forename: Tianwei
authors.initials: T
authors.lastname: Li
authors.forename: Evgenij
authors.initials: E
authors.lastname: Evdokimov
authors.forename: Rong-Fong
authors.initials: RF
authors.lastname: Shen
authors.forename: Chien-Chung
authors.initials: CC
authors.lastname: Chao
authors.forename: Ephrem
authors.initials: E
authors.lastname: Tekle
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Earl R
authors.initials: ER
authors.lastname: Stadtman
authors.forename: David C H
authors.initials: DC
authors.lastname: Yang
authors.forename: P Boon
authors.initials: PB
authors.lastname: Chock
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D040901:Proteomics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D028861:Nuclear Pore Complex Proteins; D011994:Recombinant Proteins; D025841:Small Ubiquitin-Related Modifier Proteins