Proteasome subunit beta type-8 as known as 20S proteasome subunit beta-5i is a protein that in humans is encoded by the PSMB8 gene.[4][5][6] This protein is one of the 17 essential subunits (alpha subunits 1–7, constitutive beta subunits 1–7, and inducible subunits including beta1i, beta2i, beta5i) that contributes to the complete assembly of 20S proteasome complex. In particular, proteasome subunit beta type-5, along with other beta subunits, assemble into two heptameric rings and subsequently a proteolytic chamber for substrate degradation. This protein contains "Chymotrypsin-like" activity and is capable of cleaving after large hydrophobic residues of peptide.[7] The eukaryotic proteasome recognized degradable proteins, including damaged proteins for protein quality control purpose or key regulatory protein components for dynamic biological processes. The constitutive subunit beta1, beta2, and beta 5 (systematic nomenclature) can be replaced by their inducible counterparts beta1i, 2i, and 5i when cells are under the treatment of interferon-γ. The resulting proteasome complex becomes the so-called immunoproteasome. An essential function of the modified proteasome complex, the immunoproteasome, is the processing of numerous MHC class-I restricted T cell epitopes.[8]
- ^ a b c ENSG00000206298, ENSG00000230034, ENSG00000235715, ENSG00000231631, ENSG00000204264, ENSG00000226201, ENSG00000236443 GRCh38: Ensembl release 89: ENSG00000230669, ENSG00000206298, ENSG00000230034, ENSG00000235715, ENSG00000231631, ENSG00000204264, ENSG00000226201, ENSG00000236443 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ Bodmer JG, Marsh SG, Albert ED, Bodmer WF, Dupont B, Erlich HA, Mach B, Mayr WR, Parham P, Sasazuki T (Apr 1992). "Nomenclature for factors of the HLA system, 1991. WHO Nomenclature Committee for factors of the HLA system". Tissue Antigens. 39 (4): 161–73. doi:10.1111/j.1399-0039.1992.tb01932.x. PMID 1529427.
- ^ Schmidt M, Zantopf D, Kraft R, Kostka S, Preissner R, Kloetzel PM (Apr 1999). "Sequence information within proteasomal prosequences mediates efficient integration of beta-subunits into the 20 S proteasome complex". Journal of Molecular Biology. 288 (1): 117–28. doi:10.1006/jmbi.1999.2660. PMID 10329130.
- ^ "Entrez Gene: PSMB8 proteasome (prosome, macropain) subunit, beta type, 8 (large multifunctional peptidase 7)".
- ^ Coux O, Tanaka K, Goldberg AL (November 1996). "Structure and functions of the 20S and 26S proteasomes". Annual Review of Biochemistry. 65: 801–47. doi:10.1146/annurev.bi.65.070196.004101. PMID 8811196.
- ^ Basler M, Kirk CJ, Groettrup M (Feb 2013). "The immunoproteasome in antigen processing and other immunological functions". Current Opinion in Immunology (Submitted manuscript). 25 (1): 74–80. doi:10.1016/j.coi.2012.11.004. PMID 23219269.