Proteasome Assembly Chaperone 1 (PSMG1)

The deduced 288-amino acid DSCR2 protein contains 2 transmembrane helices. Northern blot analysis detected high expression of a 1.3-kb DSCR2 transcript in testis and in the Jurkat leukemia cell line. RT-PCR analysis detected DSCR2 mRNA in brain, colon, leukocytes, breast, and testis, as well as in all fetal tissues tested. Vidal-Taboada et al. (2000) cloned the mouse Dscr2 gene and found that it is widely expressed in adult mouse tissues and throughout all stages of mouse embryo development. PAC1 and PAC2 associate as heterodimers with proteasome precursors and are degraded after formation of the 20S proteasome is completed. Overexpression of PAC1 or PAC2 accelerates the formation of precursor proteasomes, whereas knockdown by short interfering RNA impairs it, resulting in poor maturation of 20S proteasomes.