Flashcards in deck_662781 Deck (19)
At what part of teh cell does signal transduction tend to take place?
At the edge of the cell
What does adenylyl cycles cause the conversion of?What does this effector do?
ATP to cAMP-- uses ~1% of cells ATP concentrationcAMP causes the action of cAMP dependent protein kinase (PKA)-- binding of cAMP to regulatory subunits activates catalytic subunits which phosphorylate target proteins in the cell
What does phospholipase C cause the conversion of?
PIP2 to IP3 and DAG
What does phosphonositide 3-kinase cause the conversion of?
PIP2 to PIP3
What does cGMP phosphodiesterase cause the conversion of?
Cyclic GMP to 5'GMP
Which receptors have an effect on adenylyl cyclase?
Gs-coupled receptors-- β-adrenoceptors-- D1 dopamine receptors -- H2 histamine receptorsGi coupled receptors-- α2-adrenoceptors-- D2 dopamine receptors -- μ-opioid receptors
What receptors have an effect on phospholipase C?
Gq-coupled receptors-- α1-adrenoceptors-- M1 muscarinic receptors -- H1 histamine receptors
How are signals amplified?
The enzyme in the reactions causes a multiple product molecules, which causes the amplification
Describe the action of phospholipase C
Catalyses the cleavage of PIP2 into IP3 and DAG1. Agonist binds and causes a conformational change2. GTP for GDP eachange takes place3. Alpha-q GTP activates PLC4. PLC cleaves PIP2 to IP3 and DAG
What does IP3 cause?
Opens IP3 receptorcauses Ca2+ to flow into cytoplasm from SR/ER
Describe positive ionotropy in the heart
Adrenaline in the blood and noradrenaline bind to B1 adrenoceptors in the ventricular walls --> releases cAMP --> activates PKA --> phosphorylates and activates VOCC --> increase [Ca] --> Ca induced Ca releaseALSO -- alpha-s GTP directly interacts with VOCCs
Describe arteriolar vasoconstriction
Noradrenaline binds to alpha1 adrenoceptors, stimulating phopholipase C-- generates InsP3 (releases ER Ca2+) giving a contractile response-- DAG activates protein kinase which phosphorylates target proteins to maintain the vasoconstriction
The action of what hormone causes venoconstriction on which receptors?
noradrenaline acts on alpha1 adrenoceptors to cause venoconstriction
The action of what hormone causes bronchoconstriction on which receptors?
Parasympathetic ACh acts on M3 muscarinic receptors
Where else can smooth muscle be contracted?
GI tract and genitio-urinary smooth muscle
Though which effector does smooth muscle contraction come about?
Gq phospholipase C to IP3 (Ca2+) and DAG (PKC)-- Increasing [CA] will increase contractility
What regulates neurotransmitter release?
presynaptic G protein- coupled receptors are regulators in both the PNS and CNS
How is neurotransmitter release regulated?
G-beta/gamma subunits inhibit specific types of VOCCs reducing Ca2+-influx which limits neurotransmitter release