Between heartbeats, influx of positively charged sodium ions causes a slow rise in the resting membrane potential in the positive direction. 

TLS Online TPP Program

#Id: 1991

#Unit 3. Fundamental Processes

Polyadenylation requires a protein complex that contains a specificity factor, an endonuclease, and poly(A) polymerase.

 

TLS Online TPP Program

#Id: 1992

#Unit 3. Fundamental Processes

Binding of polyadenylation factors takes place when CTD Ser2 phosphorylated.

TLS Online TPP Program

#Id: 1993

#Unit 3. Fundamental Processes

Phosphorylation on Ser2 by P-TEFb activates elongation, splicing and polyadenylation

TLS Online TPP Program

#Id: 1994

#Unit 3. Fundamental Processes

The polyadenylation site has two cis-acting signals: 

An upstream AAUAAA motif, which is usually located 11 to 30 nucleotides from the site  A downstream U-rich or GU-rich element.

TLS Online TPP Program

#Id: 1995

#Unit 3. Fundamental Processes

The AAUAAA is needed for cleavage and polyadenylation because deletion or mutation of the AAUAAA hexamer prevents generation of the polyadenylated 3’ end

TLS Online TPP Program

#Id: 1996

#Unit 3. Fundamental Processes

AAUAAA motif- CPSF CPSF 73 (CF1 & CFII)- Poly A site GU element- CstF