The nomenclature of genes encoding subunits of the 26S proteasome of D. melanogaster have been standardized according to FBrf0215459. These symbols/names largely follow those used already in FlyBase, and largely mirror fly community usage. HOWEVER, note that at least one other nomenclature system exists that is followed by the HUGO Gene Nomenclature Committee (HGNC), for example, with the unfortunate result that several D. melanogaster genes have shared synonyms.

FlyBase curator comment: FBrf0044478 showed that lesions in the gene corresponding to the CG10484 annotation reduce the activity of the A2 component of phenol oxidase originally described in FBrf0017315, while the A1 and A3 phenol oxidase components originally described in FBrf0017315 are unaffected in these mutant alleles. Thus FBrf0044478 states that the mutants probably identify a structural locus for the A2 phenol oxidase component and designated this locus "Diphenol oxidase-A2, Dox-A2". However, cloning of the gene in FBrf0054017 revealed that the encoded protein had no homology to non-insect phenol oxidases at that time, but instead shows high amino acid identity (57% over the entire length of the D. melanogaster protein) to the mouse Psmd3 gene (accession number MGI:48687), which encodes a proteasome subunit. FBrf0128494 showed that the protein encoded by the CG10484 annotation is a subunit of the regulatory complex of the 26S proteasome in D. melanogaster. FBrf0058767 suggests that the A2 component of phenol oxidase seen in FBrf0017315 could have been an artificial derivative produced from either the A1 or A3 components by the activity of endogenous proteases during extraction, since protease inhibitors were not used in sample preparation (the A2 phenol oxidase component was not detected in FBrf0058767 where serine proteases inhibitors were present during sample preparation). Alternatively, FBrf0027144 shows that the speck (sp) mutants have a marked decreased in the amount of the A2 component of phenol oxidase, and thus FBrf0044480 notes that the A2 component may be a dimer of two non-identical subunits coded for by "Dox-A2" and sp. Given the uncertainty over whether the gene corresponding to the CG10484 annotation does encode a structural locus for the A2 component of phenol oxidase, but the good evidence that it is a proteasome subunit, the gene has been renamed to "Rpn3, Regulatory particle non-ATPase 3" following the nomenclature used in FBrf0152082, which uses the nomenclature used for S. cerevisiae proteasome regulatory particle subunits described in PubMed:9697412. In addition, the annotation corresponding to the gene has been renamed from CG10484 to CG42641 in release 5.22 of the genome annotation.

The "Dox-A2" locus may encode a structural locus for the A2 component of diphenol oxidase. The speck (sp) locus may also be a structural gene for the A2 component (FBrf0027144), so the A2 component may be a dimer of two non-identical subunits.

Mutations at the Dox-A2 locus alter only the activity of the A2 component of phenol oxidase, thus Dox-A2 probably identifies a structural locus for the A2 component.

RNAi generated by PCR using primers directed to this gene causes a cell growth and viability phenotype when assayed in Kc167 and S2R⁺ cells.

In a sample of 79 genes with multiple introns, 33 showed significant heterogeneity in G+C content among introns of the same gene and significant positive correspondence between the intron and the third codon position G+C content within genes. These results are consistent with selection adding against preferred codons at the start of genes.

Located between coordinates -64.5 and -62.8.