2nd messengers Flashcards
How many isoforms of Adenylyl cyclase (AC) exist?
9
All 9 form of (AC) are stimulated by?
Galpha(s)
Which form are inhibited by Galpha(i)
V and VI
Does the Gbetagamma dimer stimulate or inhibit AC?
Both.
Guanylyl cyclase make which 2nd messenger?
cGMP.
Differentiate between type 1 and type 2 guanylyl cyclase
type 1 is membrane bound, has a ligand binding site.
Type 2 is soluble.
What degrades cAMP and cGMP. Is it selective?
Phosphodiesterase (PDEs) degrades them into 5’ AMP and GMP, inactive.
Some PDEs degrade both cAMP and cGMP, others degrade one or the other.
Which sensory system uses PDEs?
Olfaction.
PDE2 breaks down cAMP. PDE2 is activated by cGMP.
Explain serotonin signaling mechanism.
Binds to a GPCR, which causes Galpha(s) to activate AC which in turns makes cAMP rise, until phosphodiesterase gets it all locked down and under control again.
Explain protein kinase A (PKA) regulation.
PKA is made of four subunits. two regulatory, which bind cAMP, and two catalytic. Catalytic are kept inactive until cAMP binds and allows them to disassociate from their regulatory domains.
Explain possible longterm and shortterm affects of PKAs.
PKA can activate through phosphorylation proteins in the cytosol causing a short term affect.
PKA can also activate KREB the same way, which will bind a CREB-binding protein and then activate gene transcription.
What does CREB stand for?
cAMP response element binding.
What is a cAMP response element?
It is a stretch of dna in the promoter region which activates a gene when bound to by a CAMP with cAMP binding protein.
How many phosphoinositides are there?
7 possible
PI-4-5-P2 is what makes IP3 and DAG.
What does IP3 do?
opens Endoplasmic Reticulum Calcium channels.
