19S regulatory particle

Three other components that my laboratory has identified and partially purified from Fraction 2 of reticulocytes, termed CF1-CF3, are involved in the degradation of proteins ligated to ubiquitin [24]. These are apparently subcomplexes of the 26S proteasome, a large ATP-dependent protease complex first described by Re-chsteiner and co-workers [25], CF3 is identical to the 20S proteasome core particle [26], while CFl and CF2 may be similar to the base and lid subcomplexes of the 19S regulatory particle of the 26S proteasome, described more recently by the Finley laboratory [27], In hindsight, the reason for finding subcomplexes, rather than the complete 26S complex in Fraction 2 was technical we have routinely prepared Fraction 2 from ATP-depleted reticulocytes [20], under which conditions the 26S proteasome dissociates to its subcomplexes. We found that incubation of the three subcomplexes in the presence of ATP promotes their assembly to the 26S proteasome [24, 26]. The role of ATP in the assembly of the 26S proteasome complex remains unknown. 

Kimuea, Y. et al. N-Terminal modifications of the 19S regulatory particle subunits of the yeast proteasome. Arch Biochcm Biophys 2003, 409, 341-8. 

I 7 7 Proteasome Regulator, PA700 (19S Regulatory Particle) Tab. n.1. Component Subunits of PA700/19S RP. 

A proteasome has two components. First, the 20S catalytic core is a hollow cylinder in which proteolysis occurs. Second, the core is flanked by 19S regulatory particles, the protein subunits of these form a lid and baselike structure (Fig. 6-7). 

The final destination for the majority of polyubiquitinated proteins in the cell is the multicatalytic protease known as the 26S proteasome (Figure 3.3). This high molecular mass enzyme is composed of two primary components the 20S catalytic particle, and the 19S regulatory particle. The 20S catalytic particle... 

Fig. 13.4 Diagrammatic representation of the proteasome and its role in protein degradation via the uhiquitin-proteasome pathway. After being tagged with ubiquitin and unfolded for degradation on the 19S regulatory particles which aid the opening of a proteolytic gate in the 20S cote, proteins ate degraded into small peptides in the barrel-shaped core where pi caspase-, p2 trypsin-, and p5 chymo-trypsin-like activities reside. Regulatory particles are...

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