A common feature of all DNA polymerases is that they cannot initiate synthesis of a chain of DNA de novo, but can only elongate a chain.

TLS Online TPP Program

#Id: 9041

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9042

#Unit 4. Cell Communication and Cell Signaling

Heterotrimeric G proteins directly bind to and are activated by G protein coupled receptors.

TLS Online TPP Program

#Id: 9043

#Unit 4. Cell Communication and Cell Signaling

Switching mechanism of monomeric G proteins 

“On” state, switch I and switch II, are bound to the terminal γ phosphate of GTP with the backbone amide groups of conserved T & G.

TLS Online TPP Program

#Id: 9044

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9045

#Unit 4. Cell Communication and Cell Signaling

Switching mechanism of monomeric G proteins 

“Off” state, Removal of the γ phosphate by GTPase-catalyzed hydrolysis causes switch I and switch II to relax into a different conformation

TLS Online TPP Program

#Id: 9046

#Unit 4. Cell Communication and Cell Signaling

Monomeric G proteins, including Ras and various Ras-like proteins, do not directly bind to receptors but act as intermediate proteins in signal transduction pathways.