video 4 second messengers Flashcards
what is the first step in regulating PKA regulation gene transcription
-free catalytic enzymes from the
PKA can translocate from cytosol into the nucleus
which 4 different receptors can activate phospholipase C signalling
PLC
DAG/IP3
Ca2+
PKC
what does the ER membrane acts as a store for?
calcium
what does IP3 do
diffuse through cells and bind to specific ion channels located in the membrane of endoplasmic reticulum
what chemical does IP3 binding allow the release of
calcium
what does IP3 increase
increases intracellular cytosolic calcium within the cell
what is the function of calcium
-acts as a second messenger
what activity does calcium regulate
the activity of some cellular proteins (some PKC proteins)
if you add _____to a cell surface receptor, calcium stored in the ER is released within milliseconds
a ligand
what protein does DAG activate
kinase C family members
PKC family members are regulated by both…?
calcium and DAG
the binding of both calcium and DAG creates a conformational change in an enzyme that does what
activates its catalytic activity
what is MAPK an abbreviation of
Mitogen Activated Protein KInase
List the pathway within MAPK signalling pathway
Ligand-receptor-first intracellular target-effector-downstream targets
how is information amplified so that small inputs can yield large changes in output
on biological systems a specific threshold must be reached for an outcome to occur
Name the 3 factors that affect whether a signalling pathway reaches its threshold
- production and breakdown of second messengers
- if a ligand remains bound to the receptor for too long, the receptor-ligand complex internalised by endocytosis and broken down inside the cell
- positive and negative feedback loops affect the strength of a signalling pathway
what happens when you increase the ligand concentration in a cell (amplifying a signalling pathway)
- if you increase the concentration of a ligand within a population, every single cell in the population responds to the ligand–more and more receptors in each individual cell are being activated
- If a few cells in the population respond to a ligand and all of the receptors get activated, you fully activate the signalling pathway within that cell, you reach the biological outcome instantly-on/off scenario
name the 4 amplification mechanisms involving enzymes
-turning a small input into a large output (e.g. binding of adrenaline to adrenoreceptors results in the synthesis of many cyclic AMP molecules
-2 camp can activate on PKA catalytic subunit
-Each pka catalytic subunit can phosphorylate multiple target molecules
-second level of amplification can involve several reactions in which the product of one reaction can activate an enzyme downstream
-
what is the overall biological output of a pathway regulated by
feedback loops
name the steps in positive feedback loops
- downstream target ‘B’ thats regulated by upstream molecule ‘A’
- molecules B has a positive feedback loop - activates A even further
- this results in a stonger signal
name the steps in negative feedback loop
- downstream target B regulated by upstream molecule A
- molecule B has a negative feedback loop - inhibits A
- results in a weaker signal
