Chaperone protein which promotes assembly of the 20S proteasome as part of a heterodimer with PSMG2. The PSMG1-PSMG2 heterodimer binds to the PSMA5 and PSMA7 proteasome subunits, promotes assembly of the proteasome alpha subunits into the heteroheptameric alpha ring and prevents alpha ring dimerization.
Subcellular locations: Cytoplasm, Endoplasmic reticulum
In the adult, detected in brain, colon, leukocytes, breast and testis. Widely expressed in the fetus. Also expressed in a variety of proliferating cell lines.