Signal Transduction Flashcards
What happens when a polar signal molecule is used?
Can’t cross lipid bilayer, binds to receptors on membrane triggers a signal cascade
Describe the signal cascade?
Extracellular signal, receptor, intermendiates( kinases or enzymes) target then response
What can epinephrine do?
Intestinal ,uncle relaxation Release of lipase Constrict blood flow Increased heart rate Skeletal muscle glycogen breakdown Liver glycogen breakdown
What do multi step Pathways allow for?
Amplification of signal and regulation of. Each step.
What are the components of signaling pathways?
Extracellular singnals
Targets of signaling molecules
Membrane receptors.
What a the various membrane receptors?
Ligand gated ion channels
GCPRS
RTKS
Describe GCPRS
Made up of G proteins. Heterotomeric G protein. Activated by GTP and inactivated by GDP.
GIalpha activates adenylate cyclase
GS alpha is inhibitory.
Describe RTKS
Recepor has built In Kinase which is activated by a signal
Requires receptor aggregation
Receptors halves cross phoshporylate
Signaling complex builds around activated RTK.
Can involve monomeric G protein.
What is involved I. The cyclic amp cascade?
Second messenger cAMP
Produced by adenylate cyclase
Broken down by phosphodieterase
What is the cyclic amp cascade?
Signal to GCPR Activate G alpha A (heterotrimeric G protein) Activate adenylate cyclase Produce camp Activate protein kinase a(PKA)
What is the membrane lipid that plays a role in signaling? What role does it play?
Phosphodidylinositol 2 phosphate (PIP2)
Second messenger
How is PIP 2 made into a 2nd messenger?
It is cleaved I to phospholipase C to activate
What is DAG and what does it do?
Diacgylcerol.
Activates protein kinase c (PLC)
What happens after PIP2 Is cleaved?
DAG activates PKC
IP3 releases ca from ER storage via a ligand gated ion channel
Ca acts as a regulator
Binds to calmodulin leading to a conformational change
Ca/ calmodulin binds binds cam kinase
What does the binding of cam kinase result in?
Release of neurtotransmitter vesicles in axon tip
What are the two types of phospholipase c?
PLC- beta activated by heterotrimeric G protein
RTK- gamma activated by tyrosine kinase
What is the IP3/DAG core pathway?
Signal GCPR GDP to GTP heterotrimeric g alpha a PLC3 IP3 to ca and calmodulin to activate cam kinase DAG to PKA
What is the pip2 pathway number 2
Used in cell survival signals
Two versions. GCPR and RTK
Pip3 activates PKB- protein kinase B
What is the map kinase/ RTK receptor pathway?
Used in growth factors Signal RTK ( dimerization, cross phosphorylation and complex formation) Activate monomeric G protein (remove GDP and add GTP) Active at map KKK Activate all the way to map K Phoshporylate transcription factors Alter gene expression
What are used for signaling?
Steroids and horomones
Non polar signals.
