Alternative titles; symbols
HGNC Approved Gene Symbol: PSMC2
Cytogenetic location: 7q22.1 Genomic coordinates (GRCh38): 7:103,347,524-103,369,395 (from NCBI)
The 26S proteasome (see PSMC1; 602706) is a multisubunit protease complex composed of a 20S core component and two 19S regulatory complexes. PSMC2 is 1 of 6 putative ATPases contained within the regulatory complex. PSMC2 was first identified as a possible cellular factor that cooperates with the human immunodeficiency virus-1 (HIV-1) protein Tat, a potent activator of virus gene expression.
By transcomplementation of a yeast sgv1-deficient mutant, Shibuya et al. (1992) isolated a human cDNA from a novel gene, MSS1. The MSS1 protein was found to share 42% sequence identity with the human TBP1 protein (PSMC3; 186852), which binds Tat in vitro and suppresses Tat-mediated transactivation in vivo (Nelbock et al., 1990). Shibuya et al. (1992) found that the levels of HIV activation by Tat correlated with endogenous levels of MSS1 mRNA. Furthermore, they provided evidence that expression of MSS1 enhances the Tat-mediated transactivation. The 1.5-kb MSS1 cDNA encodes a protein of 433 amino acids.
To characterize components of the 26S proteasome, Dubiel et al. (1993) performed peptide sequence analysis on subunit 7 (S7). They determined that S7 is identical to MSS1. By SDS-PAGE, S7 has a molecular mass of 49 kD.
By Western blot analysis of rat tissues, Yanagi et al. (2000) found that the level of PSMC2 expression varied among tissues but was ubiquitous. This was in contrast to the expression pattern of the 30-kD component of the proteasome 20S core, which showed similar levels of expression in all tissues. Immunolocalization of proteasome subunits in HeLa and HepG2 cells showed proteasome localization within nuclei, while immunolocalization of PSMC2 gave homogeneous staining of both cytoplasm and nucleoplasm. By glycerol gradient sedimentation, Yanagi et al. (2000) found PSMC2 purified from rat liver nuclear extracts associated with the proteasome and with protein complexes of lighter density, and it also existed as a monomer. They also found that several basal transcription factors for RNA polymerase II, including TATA box-binding protein (TBP; 600075), and the general transcription factors IIB (GFT2B; 189963), IIH (see GTF2H1; 189972), and IIF (see GTF2F1; 189968) coimmunoprecipitated with PSMC2 from rat liver lysosomes, suggesting dual functionality of PSMC2.
Tanahashi et al. (1998) mapped the PSMC2 gene to 7q22.1-q22.3 by fluorescence in situ hybridization.
Dubiel, W., Ferrell, K., Rechsteiner, M. Peptide sequencing identifies MSS1, a modulator of HIV Tat-mediated transactivation, as subunit 7 of the 26 S protease. FEBS Lett. 323: 276-278, 1993. [PubMed: 8500623] [Full Text: https://doi.org/10.1016/0014-5793(93)81356-5]
Nelbock, P., Dillon, P. J., Perkins, A., Rosen, C. A. A cDNA for a protein that interacts with the human immunodeficiency virus Tat activator. Science 248: 1650-1653, 1990. [PubMed: 2194290] [Full Text: https://doi.org/10.1126/science.2194290]
Shibuya, H., Irie, K., Ninomiya-Tsuji, J., Goebl, M., Taniguchi, T., Matsumoto, K. New human gene encoding a positive modulator of HIV Tat-mediated transactivation. Nature 357: 700-702, 1992. [PubMed: 1377363] [Full Text: https://doi.org/10.1038/357700a0]
Tanahashi, N., Suzuki, M., Fujiwara, T., Takahashi, E., Shimbara, N., Chung, C. H., Tanaka, K. Chromosomal localization and immunological analysis of a family of human 26S proteasomal ATPases. Biochem. Biophys. Res. Commun. 243: 229-232, 1998. [PubMed: 9473509] [Full Text: https://doi.org/10.1006/bbrc.1997.7892]
Yanagi, S., Shimbara, N., Tamura, T. Tissue and cell distribution of a mammalian proteasomal ATPase, MSS1, and its complex formation with the basal transcription factors. Biochem. Biophys. Res. Commun. 279: 568-573, 2000. [PubMed: 11118327] [Full Text: https://doi.org/10.1006/bbrc.2000.3969]