Eukaryotic cells have two isozymes of aconitase

• The mitochondrial isozyme (convert citrate to isocitrate in the citric acid cycle)

• The cytosolic isozyme 

TLS Online TPP Program

#Id: 2404

#Unit 3. Fundamental Processes

The Gre factors/TF11S enable the polymerase to cleave a few ribonucleotides from the 3' terminus of the RNA product, thereby allowing the catalytic site of RNA polymerase to be realigned with the 3' -OH.

TLS Online TPP Program

#Id: 2405

#Unit 3. Fundamental Processes

An arrested RNA polymerase can restart transcription by cleaving the RNA transcript to generate a new 3' end.

TLS Online TPP Program

#Id: 2406

#Unit 3. Fundamental Processes

RNA polymerase performs two proofreading functions on that growing transcript

pyrophosphorolytic editing

hydrolytic editing

TLS Online TPP Program

#Id: 2407

#Unit 3. Fundamental Processes

In the Pyrophosphorolytic editing, the enzyme uses its active site, in a simple back-reaction, to catalyze the removal of an incorrectly inserted ribonucleotide, by reincorporation of PPi.

TLS Online TPP Program

#Id: 2408

#Unit 3. Fundamental Processes

Hydrolytic editing, is the polymerase backtracks by one or more nucleotides and cleaves the RNA product, removing the error-containing sequence.

TLS Online TPP Program

#Id: 2409

#Unit 3. Fundamental Processes

Hydrolytic editing is stimulated by Gre factors, which both enhance hydrolytic editing function and serve as elongation stimulating factors.