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Protein A003584
Author-entered Data
V1.0, Peer Reviewed
Published 17 May 2005
Automated Data
Not Reviewed
As At Publication
Automated Data
Not Reviewed
Latest from 6 Jun 2014

UCSD Nature Molecule Pages
Published online: 17 May 2005 | doi:10.1038/mp.a003584.01


Basis Sequence: Mouse

H. Garrett R Thompson1, James P Brody1

1Department of Biomedical Engineering, University of California, Irvine, CA 92697, US.

Correspondence should be addressed to James P Brody:

Protein Function

Rpn8, also known as S12, has a relative molecular mass of 36,600 (Mr 36.6K) and is 96% identical to the mouse protein encoded by Mov-34. Mov-34 is a mutation occasionally found in the mouse, caused by retroviral integration, that is embryonic lethal. Rpn8 is well conserved among all known eukaryotes.

Rpn8 is a non-ATPase component of the lid subassembly of the 19S regulatory complex (also known as PA700 or the regulatory particle). Two 19S regulatory complexes bind to each end of the 20S proteasome to form the 26S proteasome. The proteins that assemble to form the proteasome are similar. Rpn8 is most closely related to the protein encoded by Rpn11, which has deubiquitinating activity. Rpn8 lacks this enzymatic activity.

The exact function of Rpn8 is unknown, but several domains and motifs for Rpn8 have been identified. These include the C-terminal KEKE motif, a putative site of protein-protein interaction; the Jun activation-domain binding protein (JAB) domain, originally described as a regulator of transcription; the MPR1p and PAD1p N-terminal (MPN) domain, which, along with surrounding sequences, has been shown to be important for pairing with S13 (Rpn11/POH1); and there is possibly even weak homology to a MAPKK activation loop motif.

In summary, the exact function of Rpn8 is unknown; however, it is essential to development. It is probably involved with protein degradation and possibly with transcription.

Regulation of Activity

No information is yet available on the regulation of Rpn8 activity.

Interactions with Ligands and Other Proteins

The unphosphorylated form of Rpn8 associates with the 26S proteasome complex, but the phosphorylated form does not.

Regulation of Concentration

No information is yet available on the regulation of concentration of Rpn8.

Subcellular Localization

The only direct subcellular localization measurements of unphosphorylated Rpn8 have shown that it is cytosolic and localized around the nucleus. Similar direct measurements of phosphorylated Rpn8 determined that it is cytosolic also. This was determined using an antibody raised against amino acids 1-205 of recombinant Rpn8 to localize the 26S proteasome in human JU77 mesothelioma cells.

Many studies have examined the subcellular localization of the 19S complex and the complete 26S proteasome, with conflicting results. Proteasomes can be localized to the nucleus or the cytoplasm or are sometimes associated with the endoplasmic reticulum. The different observations can be attributed to different cell types and transport during the cell cycle or during development. It is thought that proteasomes are actively translocated to different cellular compartments, but neither the mechanism nor the significance of this is known.

Major Sites of Expression

No systematic study of the major sites of expression of Rpn8 has been performed. However, it is expected to be expressed ubiquitously. It has specifically been observed in rat livers.


The expression of this protein has been measured in ten breast epithelial cell lines, five representative of breast cancer and five representative of normal breast tissue. The unphosphorylated form of Rpn8 was present in all ten cell lines. Phosphorylated Rpn8 was present in all five of the normal breast cell lines, but it was absent in all five of the breast cancer cell lines. Hence, phosphorylated Rpn8 is associated with the normal breast tissue phenotype, while the absence of phosphorylated Rpn8 is associated with the breast cancer phenotype.

Splice Variants

No information is yet available on splice variants of Rpn8.


Dubiel and others (1995) have produced two antibodies. The first is against a fragment consisting of the first 95 amino acids of Rpn8; the second is against a fragment containing the first 205 amino acids.

Abcam Inc. sells a polyclonal antibody raised in rabbit. It was generated against a synthetic peptide corresponding to amino acids 55-66 of the protein.

Affiniti Research Products Ltd. sells a sheep polyclonal antibody raised against amino acids 1-205 of a recombinant unphosphorylated Rpn8 protein.

PM IDAuthorsTitleJournalPub Date
10657252Brooks P, Fuertes G, Murray RZ, Bose S, Knecht E, Rechsteiner MC, Hendil KB, Tanaka K, Dyson J, Rivett JSubcellular localization of proteasomes and their regulatory complexes in mammalian cells.Biochem J,
346 Pt 1
15 Feb 2000
7729561Dubiel W, Ferrell K, Dumdey R, Standera S, Prehn S, Rechsteiner MMolecular cloning and expression of subunit 12: a non-MCP and non-ATPase subunit of the 26 S protease.FEBS Lett,
363, 1-2
17 Apr 1995
10363659Enenkel C, Lehmann A, Kloetzel PMGFP-labelling of 26S proteasomes in living yeast: insight into proteasomal functions at the nuclear envelope/rough ER.Mol Biol Rep,
26, 1-2
Apr 1999
9799224Enenkel C, Lehmann A, Kloetzel PMSubcellular distribution of proteasomes implicates a major location of protein degradation in the nuclear envelope-ER network in yeast.EMBO J,
17, 21
2 Nov 1998
11742986Fu H, Reis N, Lee Y, Glickman MH, Vierstra RDSubunit interaction maps for the regulatory particle of the 26S proteasome and the COP9 signalosome.EMBO J,
20, 24
17 Dec 2001
2209467Gridley T, Gray DA, Orr-Weaver T, Soriano P, Barton DE, Francke U, Jaenisch RMolecular analysis of the Mov 34 mutation: transcript disrupted by proviral integration in mice is conserved in Drosophila.Development,
109, 1
May 1990
8034024Realini C, Rogers SW, Rechsteiner MKEKE motifs. Proposed roles in protein-protein association and presentation of peptides by MHC class I receptors.FEBS Lett,
348, 2
11 Jul 1994
9523120Rivett AJIntracellular distribution of proteasomes.Curr Opin Immunol,
10, 1
Feb 1998
10419517Russell SJ, Steger KA, Johnston SASubcellular localization, stoichiometry, and protein levels of 26 S proteasome subunits in yeast.J Biol Chem,
274, 31
30 Jul 1999
9535219Seeger M, Kraft R, Ferrell K, Bech-Otschir D, Dumdey R, Schade R, Gordon C, Naumann M, Dubiel WA novel protein complex involved in signal transduction possessing similarities to 26S proteasome subunits.FASEB J,
12, 6
Apr 1998
7769002Shimanuki M, Saka Y, Yanagida M, Toda TA novel essential fission yeast gene pad1+ positively regulates pap1(+)-dependent transcription and is implicated in the maintenance of chromosome structure.J Cell Sci,
108 ( Pt 2)
Feb 1995
2651460Tanaka K, Kumatori A, Ii K, Ichihara ADirect evidence for nuclear and cytoplasmic colocalization of proteasomes (multiprotease complexes) in liver.J Cell Physiol,
139, 1
Apr 1989
15221960Thompson HG, Harris JW, Brody JPPost-translationally modified S12, absent in transformed breast epithelial cells, is not associated with the 26S proteasome and is induced by proteasome inhibitor.Int J Cancer,
111, 3
1 Sep 2004