PSMD4

Description

The PSMD4 (proteasome 26S subunit ubiquitin receptor, non-ATPase 4) is a protein-coding gene located on chromosome 1.

PSMD4, also known as 26S Proteasome Regulatory Subunit Rpn10 (systematic nomenclature), is an enzyme encoded by the PSMD4 gene. It is one of the 19 essential subunits that contribute to the complete assembly of the 19S proteasome complex. The PSMD4 gene encodes a non-ATPase subunit of the 19S regulator base, subunit Rpn10. It has 10 exons and is located on chromosome band 1q21.3. Pseudogenes have been identified on chromosomes 10 and 21. The human PSMD4 protein is 41 kDa in size and composed of 377 amino acids. Its calculated theoretical pI is 4.68. Alternative splicing during gene expression generates an isoform of the protein where the amino acid sequence from 269 to 377 is missing, and the amino sequence between 255 and 268 is replaced from DSDDALLKMTISQQ to GERGGIRSPGTAGC. The 26S proteasome complex typically consists 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 sides of the barrel-shaped 20S. The CP and RPs have distinct structural characteristics and biological functions. The 20S subcomplex exhibits three types of proteolytic activities: caspase-like, trypsin-like, and chymotrypsin-like. These proteolytic active sites are located on the inner side of a chamber formed by four stacked rings of 20S subunits, preventing random protein-enzyme encounters and uncontrolled protein degradation.

PSMD4 is a component of the 26S proteasome, a multiprotein complex that degrades ubiquitinated proteins. This complex plays a vital role in maintaining protein homeostasis by removing misfolded or damaged proteins, thus preventing disruptions to cellular functions, and by removing proteins that are no longer needed. As a result, the proteasome is involved in many cellular processes, including cell cycle progression, apoptosis, and DNA damage repair. PSMD4 functions as an ubiquitin receptor subunit, recognizing and selecting ubiquitin-conjugated proteins for degradation through its ubiquitin-interacting motifs. It exhibits a preference for longer polyubiquitin chains.

PSMD4 is also known as AF, AF-1, ASF, MCB1, Rpn10, S5A, pUB-R5.

Associated Diseases

WES Whole Exome Sequencing