PSMC2

Proteasome 26S subunit, ATPase 2
Identifiers
Symbols	PSMC2 ; MSS1; Nbla10058; S7
External IDs	OMIM: 154365 MGI: 109555 HomoloGene: 2096 GeneCards: PSMC2 Gene
Gene ontology Molecular function • protein binding • ATP binding • ATPase activity • TBP-class protein binding • proteasome-activating ATPase activity Cellular component • proteasome complex • cytoplasmic mRNA processing body • nucleus • nucleoplasm • cytoplasm • cytosol • proteasome regulatory particle, base subcomplex • membrane • proteasome accessory complex • nuclear proteasome complex • cytosolic proteasome complex Biological process • G1/S transition of mitotic cell cycle • protein polyubiquitination • mitotic cell cycle • osteoblast differentiation • stimulatory C-type lectin receptor signaling pathway • antigen processing and presentation of peptide antigen via MHC class I • antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-dependent • ubiquitin-dependent protein catabolic process • regulation of cellular amino acid metabolic process • apoptotic process • DNA damage response, signal transduction by p53 class mediator resulting in cell cycle arrest • gene expression • programmed cell death • viral process • ER-associated ubiquitin-dependent protein catabolic process • anaphase-promoting complex-dependent proteasomal ubiquitin-dependent protein catabolic process • cellular nitrogen compound metabolic process • antigen processing and presentation of exogenous peptide antigen via MHC class I • regulation of apoptotic process • negative regulation of apoptotic process • small molecule metabolic process • innate immune response • positive regulation of RNA polymerase II transcriptional preinitiation complex assembly • negative regulation of ubiquitin-protein ligase activity involved in mitotic cell cycle • positive regulation of ubiquitin-protein ligase activity involved in regulation of mitotic cell cycle transition • regulation of ubiquitin-protein ligase activity involved in mitotic cell cycle • negative regulation of canonical Wnt signaling pathway • positive regulation of canonical Wnt signaling pathway • positive regulation of proteasomal protein catabolic process Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	5701	19181
Ensembl	ENSG00000161057	ENSMUSG00000028932
UniProt	P35998	P46471
RefSeq (mRNA)	NM_001204453	NM_011188
RefSeq (protein)	NP_001191382	NP_035318
Location (UCSC)	Chr 7: 103.34 – 103.37 Mb	Chr 5: 21.79 – 21.8 Mb
PubMed search

26S protease regulatory subunit 7, also known as 26S proteasome AAA-ATPase subunit Rpt1, is an enzyme that in humans is encoded by the PSMC2 gene^[1][2][3] This protein is one of the 19 essential subunits of a complete assembled 19S proteasome complex.^[4] Six 26S proteasome AAA-ATPase subunits (Rpt1 (this protein), Rpt2, Rpt3, Rpt4, Rpt5, and Rpt6) together with four non-ATPase subunits (Rpn1, Rpn2, Rpn10, and Rpn13) form the base sub complex of 19S regulatory particle for proteasome complex.^[4]

Gene

The gene PSMC2 encodes one of the ATPase subunits, a member of the triple-A family of ATPases which have a chaperone-like activity. This subunit has been shown to interact with several of the basal transcription factors so, in addition to participation in proteasome functions, this subunit may participate in the regulation of transcription. This subunit may also compete with PSMC3 for binding to the HIV tat protein to regulate the interaction between the viral protein and the transcription complex.^[3] The human PSMC2 gene has 13 exons and locates at chromosome band 7q22.1-q22.3.

Protein

The human protein 26S protease regulatory subunit 7 is 48.6kDa in size and composed of 433 amino acids. The calculated theoretical pI of this protein is 526S protease regulatory subunit 5.71. One expression isoform is generated by alternative splicing, in which 1–137 of the amino acid sequence is missing.^[5]

Complex assembly

26S proteasome complex is usually consisted of a 20S core particle (CP, or 20S proteasome) and one or two 19S regulatory particles (RP, or 19S proteasome) on either one side or both side of the barrel-shaped 20S. The CP and RPs pertain distinct structural characteristics and biological functions. In brief, 20S sub complex presents three types proteolytic activities, including caspase-like, trypsin-like, and chymotrypsin-like activities. These proteolytic active sites located in the inner side of a chamber formed by 4 stacked rings of 20S subunits, preventing random protein-enzyme encounter and uncontrolled protein degradation. The 19S regulatory particles can recognize ubiquitin-labeled protein as degradation substrate, unfold the protein to linear, open the gate of 20S core particle, and guide the substate into the proteolytic chamber. To meet such functional complexity, 19S regulatory particle contains at least 18 constitutive subunits. These subunits can be categorized into two classes based on the ATP dependence of subunits, ATP-dependent subunits and ATP-independent subunits. According to the protein interaction and topological characteristics of this multisubunit complex, the 19S regulatory particle is composed of a base and a lid subcomplex. The base consists of a ring of six AAA ATPases (Subunit Rpt1–6, systematic nomenclature) and four non-ATPase subunits (Rpn1, Rpn2, Rpn10, and Rpn13). Thus, 26S protease regulatory subunit 4 (Rpt2) is an essential component of forming the base subcomplex of 19S regulatory particle. For the assembly of 19S base sub complex, four sets of pivotal assembly chaperons (Hsm3/S5b, Nas2/P27, Nas6/P28, and Rpn14/PAAF1, nomenclature in yeast/mammals) were identified by four groups independently.^{[6][7][8][9][10][11]} These 19S regulatory particle base-dedicated chaperons all binds to individual ATPase subunits through the C-terminal regions. For example, Hsm3/S5b binds to the subunit Rpt1 (this protein) and Rpt2, Nas2/p27 to Rpt5, Nas6/p28 to Rpt3, and Rpn14/PAAAF1 to Rpt6, respectively. Subsequently, three intermediate assembly modules are formed as following, the Nas6/p28-Rpt3-Rpt6-Rpn14/PAAF1 module, the Nas2/p27-Rpt4-Rpt5 module, and the Hsm3/S5b-Rpt1-Rpt2-Rpn2 module. Eventually, these three modules assemble together to form the heterohexameric ring of 6 Atlases with Rpn1. The final addition of Rpn13 indicates the completion of 19S base sub complex assembly.^[4]

Function

As the degradation machinery that is responsible for ~70% of intracellular proteolysis,^[12] proteasome complex (26S proteasome) plays a critical roles in maintaining the homeostasis of cellular proteome. Accordingly, misfolded proteins and damaged protein need to be continuously removed to recycle amino acids for new synthesis; in parallel, some key regulatory proteins fulfill their biological functions via selective degradation; furthermore, proteins are digested into peptides for MHC class I antigen presentation. To meet such complicated demands in biological process via spatial and temporal proteolysis, protein substrates have to be recognized, recruited, and eventually hydrolyzed in a well controlled fashion. Thus, 19S regulatory particle pertains a series of important capabilities to address these functional challenges. To recognize protein as designated substrate, 19S complex has subunits that are capable to recognize proteins with a special degradative tag, the ubiquitinylation. It also have subunits that can bind with nucleotides (e.g., ATPs) in order to facilitate the association between 19S and 20S particles, as well as to cause confirmation changes of alpha subunit C-terminals that form the substate entrance of 20S complex. The ATPases subunits assemble into a six-membered ring with a sequence of Rpt1–Rpt5–Rpt4–Rpt3–Rpt6–Rpt2, which interacts with the seven-membered alpha ring of 20S core particle and eastablishs an asymmetric interface between the 19S RP and the 20S CP.^[13][14] Three C-terminal tails with HbYX motifs of distinct Rpt ATPases insert into pockets between two defined alpha subunits of the CP and regulate the gate opening of the central channels in the CP alpha ring.^[15][16]

Interactions

PSMC2 has been shown to interact with:

• NDC80,^[17]
• PSMC1,^[18][19]
• PSMC4,^[19][20] and
• PSMD5.^[18][21]

References

1. Tanahashi N, Suzuki M, Fujiwara T, Takahashi E, Shimbara N, Chung CH, Tanaka K (March 1998). "Chromosomal localization and immunological analysis of a family of human 26S proteasomal ATPases". Biochem Biophys Res Commun 243 (1): 229–32. doi:10.1006/bbrc.1997.7892. PMID 9473509.
2. Shibuya H, Irie K, Ninomiya-Tsuji J, Goebl M, Taniguchi T, Matsumoto K (July 1992). "New human gene encoding a positive modulator of HIV Tat-mediated transactivation". Nature 357 (6380): 700–2. Bibcode:1992Natur.357..700S. doi:10.1038/357700a0. PMID 1377363.
3. "Entrez Gene: PSMC2 proteasome (prosome, macropain) 26S subunit, ATPase, 2".
4. Gu ZC, Enenkel C (Dec 2014). "Proteasome assembly". Cellular and Molecular Life Sciences 71 (24): 4729–45. doi:10.1007/s00018-014-1699-8. PMID 25107634.
5. "Uniprot: P35998 - PRS7_HUMAN".
6. Le Tallec B, Barrault MB, Guérois R, Carré T, Peyroche A (Feb 2009). "Hsm3/S5b participates in the assembly pathway of the 19S regulatory particle of the proteasome". Molecular Cell 33 (3): 389–99. doi:10.1016/j.molcel.2009.01.010. PMID 19217412.
7. Funakoshi M, Tomko RJ, Kobayashi H, Hochstrasser M (May 2009). "Multiple assembly chaperones govern biogenesis of the proteasome regulatory particle base". Cell 137 (5): 887–99. doi:10.1016/j.cell.2009.04.061. PMC 2718848. PMID 19446322.
8. Park S, Roelofs J, Kim W, Robert J, Schmidt M, Gygi SP, Finley D (Jun 2009). "Hexameric assembly of the proteasomal ATPases is templated through their C termini". Nature 459 (7248): 866–70. Bibcode:2009Natur.459..866P. doi:10.1038/nature08065. PMC 2722381. PMID 19412160.
9. Roelofs J, Park S, Haas W, Tian G, McAllister FE, Huo Y, Lee BH, Zhang F, Shi Y, Gygi SP, Finley D (Jun 2009). "Chaperone-mediated pathway of proteasome regulatory particle assembly". Nature 459 (7248): 861–5. Bibcode:2009Natur.459..861R. doi:10.1038/nature08063. PMC 2727592. PMID 19412159.
10. Saeki Y, Toh-E A, Kudo T, Kawamura H, Tanaka K (May 2009). "Multiple proteasome-interacting proteins assist the assembly of the yeast 19S regulatory particle". Cell 137 (5): 900–13. doi:10.1016/j.cell.2009.05.005. PMID 19446323.
11. Kaneko T, Hamazaki J, Iemura S, Sasaki K, Furuyama K, Natsume T, Tanaka K, Murata S (May 2009). "Assembly pathway of the Mammalian proteasome base subcomplex is mediated by multiple specific chaperones". Cell 137 (5): 914–25. doi:10.1016/j.cell.2009.05.008. PMID 19490896.
12. Rock KL, Gramm C, Rothstein L, Clark K, Stein R, Dick L, Hwang D, Goldberg AL (Sep 1994). "Inhibitors of the proteasome block the degradation of most cell proteins and the generation of peptides presented on MHC class I molecules". Cell 78 (5): 761–71. doi:10.1016/s0092-8674(94)90462-6. PMID 8087844.
13. Tian G, Park S, Lee MJ, Huck B, McAllister F, Hill CP, Gygi SP, Finley D (Nov 2011). "An asymmetric interface between the regulatory and core particles of the proteasome". Nature Structural & Molecular Biology 18 (11): 1259–67. doi:10.1038/nsmb.2147. PMC 3210322. PMID 22037170.
14. Lander GC, Estrin E, Matyskiela ME, Bashore C, Nogales E, Martin A (Feb 2012). "Complete subunit architecture of the proteasome regulatory particle". Nature 482 (7384): 186–91. Bibcode:2012Natur.482..186L. doi:10.1038/nature10774. PMC 3285539. PMID 22237024.
15. Gillette TG, Kumar B, Thompson D, Slaughter CA, DeMartino GN (Nov 2008). "Differential roles of the COOH termini of AAA subunits of PA700 (19 S regulator) in asymmetric assembly and activation of the 26 S proteasome". The Journal of Biological Chemistry 283 (46): 31813–22. doi:10.1074/jbc.M805935200. PMC 2581596. PMID 18796432.
16. Smith DM, Chang SC, Park S, Finley D, Cheng Y, Goldberg AL (Sep 2007). "Docking of the proteasomal ATPases' carboxyl termini in the 20S proteasome's alpha ring opens the gate for substrate entry". Molecular Cell 27 (5): 731–44. doi:10.1016/j.molcel.2007.06.033. PMC 2083707. PMID 17803938.
17. Chen Y, Sharp ZD, Lee WH (September 1997). "HEC binds to the seventh regulatory subunit of the 26 S proteasome and modulates the proteolysis of mitotic cyclins". J. Biol. Chem. 272 (38): 24081–7. doi:10.1074/jbc.272.38.24081. PMID 9295362.
18. Gorbea C, Taillandier D, Rechsteiner M (January 2000). "Mapping subunit contacts in the regulatory complex of the 26 S proteasome. S2 and S5b form a tetramer with ATPase subunits S4 and S7". J. Biol. Chem. 275 (2): 875–82. doi:10.1074/jbc.275.2.875. PMID 10625621.
19. Hartmann-Petersen R, Tanaka K, Hendil KB (February 2001). "Quaternary structure of the ATPase complex of human 26S proteasomes determined by chemical cross-linking". Arch. Biochem. Biophys. 386 (1): 89–94. doi:10.1006/abbi.2000.2178. PMID 11361004.
20. Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T, Figeys D (2007). "Large-scale mapping of human protein-protein interactions by mass spectrometry". Mol. Syst. Biol. 3: 89. doi:10.1038/msb4100134. PMC 1847948. PMID 17353931.
21. Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP, Vidal M (October 2005). "Towards a proteome-scale map of the human protein-protein interaction network". Nature 437 (7062): 1173–8. Bibcode:2005Natur.437.1173R. doi:10.1038/nature04209. PMID 16189514.

Further reading

• Coux O, Tanaka K, Goldberg AL (1996). "Structure and functions of the 20S and 26S proteasomes". Annu. Rev. Biochem. 65: 801–47. doi:10.1146/annurev.bi.65.070196.004101. PMID 8811196.
• Goff SP (2003). "Death by deamination: a novel host restriction system for HIV-1". Cell 114 (3): 281–3. doi:10.1016/S0092-8674(03)00602-0. PMID 12914693.
• Dawson SJ, White LA (1992). "Treatment of Haemophilus aphrophilus endocarditis with ciprofloxacin". J. Infect. 24 (3): 317–20. doi:10.1016/S0163-4453(05)80037-4. PMID 1602151.
• Nacken W, Kingsman AJ, Kingsman SM, Sablitzky F, Sorg C (1995). "A homologue of the human MSS1 gene, a positive modulator of HIV-1 gene expression, is massively expressed in Xenopus oocytes". Biochim. Biophys. Acta 1261 (2): 293–5. doi:10.1016/0167-4781(95)00022-9. PMID 7711076.
• Ghislain M, Udvardy A, Mann C (1993). "S. cerevisiae 26S protease mutants arrest cell division in G2/metaphase". Nature 366 (6453): 358–62. Bibcode:1993Natur.366..358G. doi:10.1038/366358a0. PMID 8247132.
• Dubiel W, Ferrell K, Rechsteiner M (1993). "Peptide sequencing identifies MSS1, a modulator of HIV Tat-mediated transactivation, as subunit 7 of the 26 S protease". FEBS Lett. 323 (3): 276–8. doi:10.1016/0014-5793(93)81356-5. PMID 8500623.
• Seeger M, Ferrell K, Frank R, Dubiel W (1997). "HIV-1 tat inhibits the 20 S proteasome and its 11 S regulator-mediated activation". J. Biol. Chem. 272 (13): 8145–8. doi:10.1074/jbc.272.13.8145. PMID 9079628.
• Chen Y, Sharp ZD, Lee WH (1997). "HEC binds to the seventh regulatory subunit of the 26 S proteasome and modulates the proteolysis of mitotic cyclins". J. Biol. Chem. 272 (38): 24081–7. doi:10.1074/jbc.272.38.24081. PMID 9295362.
• Madani N, Kabat D (1998). "An Endogenous Inhibitor of Human Immunodeficiency Virus in Human Lymphocytes Is Overcome by the Viral Vif Protein". J. Virol. 72 (12): 10251–5. PMC 110608. PMID 9811770.
• Simon JH, Gaddis NC, Fouchier RA, Malim MH (1998). "Evidence for a newly discovered cellular anti-HIV-1 phenotype". Nat. Med. 4 (12): 1397–400. doi:10.1038/3987. PMID 9846577.
• Zheng L, Chen Y, Lee WH (1999). "Hec1p, an Evolutionarily Conserved Coiled-Coil Protein, Modulates Chromosome Segregation through Interaction with SMC Proteins". Mol. Cell. Biol. 19 (8): 5417–28. PMC 84384. PMID 10409732.
• Gorbea C, Taillandier D, Rechsteiner M (2000). "Mapping subunit contacts in the regulatory complex of the 26 S proteasome. S2 and S5b form a tetramer with ATPase subunits S4 and S7". J. Biol. Chem. 275 (2): 875–82. doi:10.1074/jbc.275.2.875. PMID 10625621.
• Mulder LC, Muesing MA (2000). "Degradation of HIV-1 integrase by the N-end rule pathway". J. Biol. Chem. 275 (38): 29749–53. doi:10.1074/jbc.M004670200. PMID 10893419.
• Hwang J, Fauzi H, Fukuda K, Sekiya S, Kakiuchi N, Shimotohno K, Taira K, Kusakabe I, Nishikawa S (2001). "The RNA aptamer-binding site of hepatitis C virus NS3 protease". Biochem. Biophys. Res. Commun. 279 (2): 557–62. doi:10.1006/bbrc.2000.4007. PMID 11118325.
• Yanagi S, Shimbara N, Tamura Ta (2001). "Tissue and cell distribution of a mammalian proteasomal ATPase, MSS1, and its complex formation with the basal transcription factors". Biochem. Biophys. Res. Commun. 279 (2): 568–73. doi:10.1006/bbrc.2000.3969. PMID 11118327.
• Hartmann-Petersen R, Tanaka K, Hendil KB (2001). "Quaternary structure of the ATPase complex of human 26S proteasomes determined by chemical cross-linking". Arch. Biochem. Biophys. 386 (1): 89–94. doi:10.1006/abbi.2000.2178. PMID 11361004.
• Sheehy AM, Gaddis NC, Choi JD, Malim MH (2002). "Isolation of a human gene that inhibits HIV-1 infection and is suppressed by the viral Vif protein". Nature 418 (6898): 646–50. Bibcode:2002Natur.418..646S. doi:10.1038/nature00939. PMID 12167863.