Turns are classified into several classes, like 

β-Turn  (I, II, I’, II’) 

α -Turn 

γ- Turn

π -Turn

#Id: 1861

#Unit 3. Fundamental Processes

 

#Id: 1862

#Unit 3. Fundamental Processes

 

#Id: 1981

#Unit 3. Fundamental Processes

This structure is called a cap.

#Id: 1982

#Unit 3. Fundamental Processes

After transcription initiation, Pol II is paused 30 nucleotides downstream from the initiation site, recruits of the capping enzymes.

#Id: 1983

#Unit 3. Fundamental Processes

Capping is done by a dimeric nuclear enzyme which has two subunits and three functions

1. Guanylyl-transferase (GT)

2. Methyltransferase (MT)

#Id: 1984

#Unit 3. Fundamental Processes