Chapter 13 Flashcards
(19 cards)
Identify the basic components of all signal-transduction pathways
Release of primary messenger Reception of primary messenger Relay of information by second messenger Activation of effectors that directly alter physiological response Termination of signal
Primary messenger
Signal molecule; message received by the cell
Secondary messenger
Intracellular chemical that relays message from ligand receptor complex
Heterotrimeric g-protein
Activated by 7TM receptor
Gαs
Activates adenylate cyclase
Protein kinase A
Stimulated by cAMP
Kinase
Enzymes that phosphorylates a substrate at expense of ATP
Phosphoralation (turns enzymes on and off by addition of phosphate)
cAMP phosphodiesterase
Results in the activation of kinase A
GTPase activity
Results in the reassociation of gα and gβψ
Cholera
Due to persistant stimulation of Gαs
Pertussis
Results from gαi inhibition
Phospholipase C
Generates two second messengers
Gαq
Activates phospholipase c
Inisital triphosphate
Activates ca2+ channel
Protein kinase c
Activated by diacylglycerol
what are the three major classes of protein receptors?
7TM, receptors that dimerize and recruit, receptors that dimerize tyrosine kinases
what are some of the structural features common to all membrane-bound receptors?
must have a site on the extracellular side of membrane where signal molecule can bind and have intracellular domain
binding of signal to receptor must induce structural changes intracellular
why is GTPase activity of G proteins crucial to proper function of a cell?
GTPase terminates the signal…without activity after a pathway has been activated, it remains activated and unresponsive to changes in inital signal
explain how small number of hormones binding to the extracellular surface of a cell can have a large biochemical effect inside of the cell
the initial signal (binding of the hormone by a receptor is amplified by channels and enzymes
