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35 Cards in this Set
- Front
- Back
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PIP2 (Phosphotidyl Inosital 4,5 bisphosphate) is produced from what molecule?
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Phosphotidyl Inosital
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The classical phosphoinosital pathyway depends on what molecule?
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PIP2
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What are the enzymes needed to make PIP2? x2
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PI 4 kinase
PI 4 phosphate 5 kinase |
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What is the name of the trimeric G protein associated with the phosphatidyl inosital pathway?
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Gq protein
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What does the Gq alpha activate?
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Phospholipase C beta
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What does activated phospholipase C do?
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Hydrolyze PIP2 and release it from membrane.
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What is the end product (second messengers) from the hydrolysis of PIP2?
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IP3
DAG |
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What does DAG do?
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Activate Protein Kinase C
with the help of calcium |
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What does IP3 do?
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Release Calcium from ER
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Describe the rate of release of calcium from the ER by IP3.
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ALL or NONE
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What are two ways to terminate the calcium response.
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1. IP3 is rapidly dephosphorylated and inactivated (short half life)
2. Cytosolic calcium is quickly pumped out. |
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What happens to IP3's that are not dephosphorylated?
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They become IP4 and promote refilling the stores for intracellular calcium
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What is the role of PKC (Protein Kinase C)?
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Activate TF for genes involved in proliferation
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Where does Phorbol Esters come from?
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Derived from croton oil
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What does phorbol esters do?
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Carcinogenic molecule that activates PKC by mimicing DAG.
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Too much croton oil does what?
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Immediate vomiting followed by griping pain leading to fatality.
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What is the medicinal use of croton oil.
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Can empty the bowels in 1 hour.
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What is an example of PKC inhibitor in metabolism?
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Ruboxistaurin
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Why is calcium used in many signaling pathways?
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1. Rapid response
2. Can induce large conformational changes 3. Suited to bind strongly to irregular shaped crevices |
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What kind of proteins bind to calcium?
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Proteins with EF hand motifs ... e.g.-calmodulin
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How many binding sites (EF motifs) for calcium is there for calmodulin?
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4
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How is calmodulin activated? what conditions?
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By the binding of 3 or 4 calciums.
Usually when cytosolic calcium levels are above 50 nM |
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T/F - Calmodulin is an enzyme.
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False
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What is the function of calmodulin?
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To serve as a component of an enzyme complex
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Give an example of a calmodulin dependent kinase.
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CaM-kinase
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CaM kinases play a role in what human activity?
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Memory and learning
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What activates CaM kinase?
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Calmodulin
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T/F - Active CaM kinase is inactivated after calcium withdrawal.
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False - it can remain active after calcium withdrawal
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When Ca2+ signal dies out, calmodulin dissociates from CaM kinase, but it is still active. Why?
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Because it converts to calcium independent form
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While paritally inactive (calmodulin removed), what completely inactivates CaM Kinase?
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Protein Phosphatase
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Two ways that cAMP and Ca2+ pathways interact?
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1. Share downstream targets
2. Some forms of cAMP phosphodiesterase and adenylyl cyclase is regulated by Ca2+/calmodulin |
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What is the only protein phosphatase that is under the control of calmodulin?
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Calcineurin
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What does calcineurin do?
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Regulator of NFAT (Nuclear Factor of Activated T-cells)
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What are the three steps in NFAT activation?
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1. Dephosphorylation
2. Nuclear Translocation 3. Affinity Increase for DNA |
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T/F - Phosphorylated NFAT is active.
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False - it is inactive
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