Identification of Proteassemblin,a Mammalian Homologue of the Yeast Protein,Ump1p, That Is Required for Normal Proteasome Assembly

摘要

We have identified a mammalian homologue of yeast Umplp by searching for similar proteins in human and mouse expressed sequence tag (EST) databases.Umplp is an accessory protein that is required for normal proteasome assembly in yeast (1).A mammalian homologue,which we refer to as "proteassemblin",is a constituent of proteasome assembly intermediates (preproteasomes),but not fully assembled 20S proteasomes, as is Umplp in yeast.We also provide evidence that proteassemblin is a constituent of pre-immunoproteasomes that contain the precursor of the interferon-#gamma#-inducible subunit LMP2.By analogy with Umplp,we hypothesize that proteassemblin is required for normal mammalian proteasome assembly.