Krüger E, Kloetzel P M, Enenkel C
Institut für Biochemie, Humboldt Universität zu Berlin, Universitätsklinikum Charité, Monbijoustr. 2, 10117, Berlin, Germany.
Biochimie. 2001 Mar-Apr;83(3-4):289-93. doi: 10.1016/s0300-9084(01)01241-x.
26S proteasomes are multi-subunit protease complexes responsible for the turnover of short-lived proteins. Proteasomal degradation starts with the autocatalytic maturation of the 20S core particle. Here, we summarize different models of proteasome assembly. 20S proteasomes are assembled as precursor complexes containing alpha and unprocessed beta subunits. The propeptides of the beta subunits are thought to prevent premature conversion of the precursor complexes into matured particles and are needed for efficient beta subunit incorporation. The complex biogenesis is tightly regulated which requires additional components such as the maturation factor Ump1/POMP, an ubiquitous protein in eukaryotic cells. Ump1/POMP is associated with precursor intermediates and degraded upon final maturation. Mammalian proteasomes are localized all over the cell, while yeast proteasomes mainly localize to the nuclear envelope/endoplasmic reticulum (ER) membrane network. The major localization of yeast proteasomes may point to the subcellular place of proteasome biogenesis.
26S蛋白酶体是负责短寿命蛋白质周转的多亚基蛋白酶复合物。蛋白酶体降解始于20S核心颗粒的自催化成熟。在此，我们总结了蛋白酶体组装的不同模型。20S蛋白酶体作为包含α亚基和未加工β亚基的前体复合物进行组装。β亚基的前肽被认为可防止前体复合物过早转化为成熟颗粒，并且是有效掺入β亚基所必需的。复杂的生物发生过程受到严格调控，这需要额外的组件，如成熟因子Ump1/POMP，它是真核细胞中一种普遍存在的蛋白质。Ump1/POMP与前体中间体相关，并在最终成熟时降解。哺乳动物蛋白酶体遍布细胞各处，而酵母蛋白酶体主要定位于核膜/内质网（ER）膜网络。酵母蛋白酶体的主要定位可能指向蛋白酶体生物发生的亚细胞位置。
