Second Messenger System and Direct Messenger System - unit 4

Cyclic AMP, Step 1

Hormone binds receptor to the hormone acting as the first messenger, binds to its receptor in the plasma membrane

Cyclic AMP, Step 2

Receptor activates G protein hormone binding causes the receptor to change shape allowing it to bind to the G protein. The G protein is activated as the guanisine diphosphate (GDP) bound to it is displaced by the high energy compound guanosine Triphosphate (GTP). G protein acts like a light switch and turns off then GDP binds and then turn on when GTP bind to it

Cyclic AMP, Step 3

G protein activated adenylate cyclase the activated G protein (moving along the membrane) binds to effector enzyme adenylate cycles some G proteins stimulate or inhibit adenylate cyclase eventually the bound GTP becomes inactive and GDP binds an turns the G Protein off

Cyclic AMP, Step 4

Adenylate cyclase ATP to cyclic AMP for as long as G protein stays active ATP continues to convert to AMP

Cyclic AMP, Step 5

Cyclic Amp activates protein kinases Camp which is free to doffs out of the cell, triggered a cascade of chemical reaction by activating protein kindness which are enemies that phosphorylate (add a phosphate group too) various proteins. Because phosphorylation activates some of these proteins and inhibits others it may affect a variety of processed=s in same target cell at the same time

- This type of intracellular enzymatic cascade has huge effect and only works briefly because of the enzyme phodiestrase

Direct Messaging, Step 1

Diffuses into target cell and binds and activates intracellular receptor

Direct Messaging, Step 2

Receptor then goes to nucleus and binds to region of DNA and this "turns on gene" and activated mRNA which is then translated into cytoplasmic ribosomes to produce certain proteins