title: Proteomic analysis of the 20S proteasome (PSMA3)-interacting proteins reveals a functional link between the proteasome and mRNA metabolism.
abstract: The 26S proteasome is a large multi-subunit protein complex that exerts specific degradation of proteins in the cell. The 26S proteasome consists of the 20S proteolytic particle and the 19S regulator. In order to be targeted for proteasomal degradation most of the proteins must undergo the post-translational modification of poly-ubiquitination. However, a number of proteins can also be degraded by the proteasome via a ubiquitin-independent pathway. Such degradation is exercised largely through the binding of substrate proteins to the PSMA3 (alpha 7) subunit of the 20S complex. However, a systematic analysis of proteins interacting with PSMA3 has not yet been carried out. In this report, we describe the identification of proteins associated with PSMA3 both in the cytoplasm and nucleus. A combination of two-dimensional gel electrophoresis (2D-GE) and tandem mass-spectrometry revealed a large number of PSMA3-bound proteins that are involved in various aspects of mRNA metabolism, including splicing. In vitro biochemical studies confirmed the interactions between PSMA3 and splicing factors. Moreover, we show that 20S proteasome is involved in the regulation of splicing in vitro of SMN2 (survival motor neuron 2) gene, whose product controls apoptosis of neurons.
authors.affiliation: Institute of Cytology, Russian Academy of Sciences, 194064 Saint-Petersburg, Russia.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Fedorova
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Moiseeva
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Nikiforov
authors.forename: Anna S
authors.initials: AS
authors.lastname: Tsimokha
authors.forename: Veronika A
authors.initials: VA
authors.lastname: Livinskaya
authors.forename: Mark
authors.initials: M
authors.lastname: Hodson
authors.forename: Andrew
authors.initials: A
authors.lastname: Bottrill
authors.forename: Irina N
authors.initials: IN
authors.lastname: Evteeva
authors.forename: Julia B
authors.initials: JB
authors.lastname: Ermolayeva
authors.forename: Irina M
authors.initials: IM
authors.lastname: Kuznetzova
authors.forename: Konstantin K
authors.initials: KK
authors.lastname: Turoverov
authors.forename: Ian
authors.initials: I
authors.lastname: Eperon
authors.forename: Nickolai A
authors.initials: NA
authors.lastname: Barlev
mesh_terms: D017398:Alternative Splicing; D003593:Cytoplasm / Q000378:metabolism; D005091:Exons; D057809:HEK293 Cells; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D059748:Proteolysis; D040901:Proteomics / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics
chemical_list: D009687:Nuclear Proteins; D012333:RNA, Messenger; C526477:SMN2 protein, human; D055540:Survival of Motor Neuron 2 Protein; C488165:PSMA3 protein, human; D046988:Proteasome Endopeptidase Complex