AAA nucleotidases

AAA nucleotidases share the common property of altering the conformation or association state of proteins, so it is not surprising that the RC has been shown to prevent aggregation of several denatured proteins including citrate synthase and ribonuclease A [59-61]. The chaperone activity of the RC may explain why the RC plays a role in transcription apparently in the absence of an attached 20S proteasome [62]. 

Sequencing of several archaeal genomes revealed the existence of genes with high sequence similarity to the ATPases of the eukaryotic 19S regulator. The deduced 50 kDa proteins have N-terminal coiled-coils, a hallmark of proteasomal AAA ATPases, and C-terminal AAA domains. The Methanococcus jannaschii protein was expressed in E. coli and purified as a 650 kD complex with nucleotidase activity. When mixed with proteasomes from Thermoplasma, degradation of substrate proteins was stimulated up to... 

Abbreviations APC anaphase-promoting complex ARC AAA ATPase-forming ring-shaped complexes eIF3 eukaryotic initiation factor 3 PAN proteasome-activating nucleotidase TFIIH basal transcription factor IIH. 

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