The prosomal RNA-binding protein p27K is a member of the α-type human prosomal gene family

Abstract

Monoclonal antibodies demonstrated high conservation during evolution of a prosomal protein of M(r) 27,000 and differentiation--specific expression of the epitope. More than 90% of the reacting antigen was found as a p27K protein in the free messenger ribonucleoprotein (mRNP) fraction but another protein of M(r) 38,000, which shared protease fingerprint patterns with the p27K polypeptide, was also labelled in the nuclear and polyribosomal fractions. Sequencing of cDNA recombinant clones encoding the p27/38K protein and comparison with another prosomal protein, p30-33K, demonstrated the existence of a common characteristic sequence pattern containing three highly conserved segments. The genes Hs PROS-27 and Hs PROS-30 were mapped to chromosomes 14 (14q13) and 11 (11p15.1), respectively. The structure of the p27K protein shows multiple potential phosphorylation sites, an NTP-binding fold and an RNA-binding consensus sequence. The Hs PROS-27/beta-galactosidase fusion protein binds a single RNA of about 120 nucleotides from total HeLa cell RNA. Sequence comparisons show that the Hs PROS-27 and Hs PROS-30 genes belong to the gene family that encodes the prosome--MCP (multicatalytic proteinase)--proteasome proteins. Comparison with other members of the family from various species allowed us to show that the tripartite consensus sequence characteristic of the alpha-type sub-family is conserved from archeobacteria to man. The members of this gene family are characterised by very high evolutionary conservation of amino acid sequences of homologous genes and 20%-35% sequence similarity, between different family member within the same species and are clearly distinct from the beta-type family.

Identification and Initial Characterization of a Specific Proteasome (Prosome) Associated RNase Activity

“…Interestingly, proteasomes always appear linked with the free mRNP particles when low salt conditions were used throughout purification (Schmid et al, 1984;Martins de Sa et al, 1986;Nothwang et al, 1992aNothwang et al, , 1992b. In addition, previously we have shown that proteasomes associated in vitro with TMV-RNA and mRNA from adenovirusinfected cells, and Bey et al (1993) have demonstrated that the 27-kDa protein, an α-type subunit of proteasomes, has one distinct mRNA binding domain. A widely accepted argument for a possible relationship among proteasomes and RNA is the presence of small RNA molecules in pure preparations of proteasomes (Arrigo et al, 1985;Martins de Sa et al, 1986).…”

Molecular cloning and characterization of a gene encoding the 29-kDa proteasome subunit from Trypanosoma cruzi

“…The highly conserved N-terminal box found in the a-subunits of the proteasome (Zwickl et al 1992), which is believed to be involved in the formation of the external pores of the particle and in the interaction with regulatory complexes (Lupas et al 1995), is also found in the T. cruzi sequence. The proteasome motif GXXXD and the a-family motif RPXG (Bey et al 1993) are also present in TCPR29A. The C-terminal region of the T. cruzi protein is rich in charged residues, a characteristic also found in the other a6 sequences.…”

Proteomic Profiling Reveals Upregulated Protein Expression of Hsp70 in Keloids

“…Prosomal P27K protein, which is not expressed in keloid fibroblasts, is involved in the regulation of cell differentiation and the cell cycle. Also, because of the proteolytic activity of this protein, it is involved in protein degradation [38, 39]. …”