The biosynthesis of chlorophylls and heme begins with the synthesis of δ‐aminolevulinic acid (ALA) from glutamic acid. 

Two molecules of ALA react to yield porphobilinogen (PBG). 

Four molecules of PBG form the ring structure of protoporphyrin IX, the common branch point for the synthesis of heme and chlorophyll. 

To make chlorophyll, a magnesium chelatase inserts Mg into the protoporphyrin IX ring

TLS Online TPP Program

#Id: 9055

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9056

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9057

#Unit 4. Cell Communication and Cell Signaling

glutamate (E200) and arginine (R209) participate in binding of cAMP, which causes a conformational change in the loop that prevents binding of the loop to the C subunit.

TLS Online TPP Program

#Id: 9058

#Unit 4. Cell Communication and Cell Signaling

Epinephrine --> Gαs-GTP-->Adenylyl cyclase-->cAMP-->PKA

TLS Online TPP Program

#Id: 9059

#Unit 4. Cell Communication and Cell Signaling

PKA always phosphorylates a serine or threonine residue that is located within the common sequence motif: X-Arg-(Arg/Lys)-X-(Ser/Thr)-Φ

TLS Online TPP Program

#Id: 9060

#Unit 4. Cell Communication and Cell Signaling

Increased cAMP; PKA active, increased glycogen breakdown, and decreased glycogen synthesis