L39- Cell signalling 2nd messenger Flashcards
What type of messengers is a ligand?
first
what do second messenger molcules do?
a receptor that activates intracellular chain of events
examples of second messenger molecules?
- Ca2+
- IP3, DAG
How does phosphoionsitol signalling occur?
- through G-protein coupling receptors, activating another effector enzyme, phospholipase c
- PIP 2 into 2 second messenger molecules, IP3 and DAG
what does IP3 do?
- it is water soluble
- acts as on receptors in the ER to release Ca2+ from intracellular stores.
what does DAG do?
- it is a lipid soluble messenger
- it activates protein kinase C (PKC)
- Phorbolesters mimic DAG to activate PKC
- DAG can also be cleaved to generate another messenger arachidonic acid
What is phosolipase c?
- it is lipid enzyme
- Catalyses the hydrolysis of phospholipids between phosphate group and chain
how does phospholipid signalling occur?
• Phosphatidylinositol 3 kinase (PI3K) acts on PIP2
• Generates PIP3 or PI-(3,4,5)P3
-involved in recruitment of proteins to the plasma membrane.
where is Ca2+ stored?
- stored in the ER
- can be stored in mitichondria and lysosomes
how does store-operated Ca2+ entry occur?
- once Ca2+ is released into the cytoplasm the store is empty
- as the store is depleted it activates a mechanism to re-fill.
what are the proteins involved in store-operated Ca+ entry?
- orai
- stim1
how many types of protein kinase c is there?
there is 10 types thatare arranged into 3 groups
what are the requirements for the differnt types of PKC?
- Conventional –DAG + Ca2+
- Novel –DAG only
- Atypical –other lipid
What is convergent signal patheways?
-activate the same second messenger
What is divergent signal patheways?
-can divergeto activate different effector proteins and diverse cell responses
