Card Set Information
Cell bio Signal Transduction
Chapter 14 Signal transduction
First messenger - Neurotransmitters & drugs
Receptor proteins - ligand binds to?
Ligand binds to multiple receptors
What is a Binding site?
Specific point of ligand & receptor
Physical & electrical fit
= neurotransmitters made by the brain
Yellow = brain cell
Paracrine proces- cell makes signals to surrounding cells
Autocrine process � cell makes signals to itself
Cell contains receptors, if the ligand fits, a cascade of chemical changes will occur to tell the DNA to make
specific proteins, enzymes, or hormones
passing of the message; message remains exactly the same
The overflow of information during cell signaling
Hydrophilic signal � prinmary messenger � Hydrophobic signal
Plasma membrane Intracelllular receptor
Lined to protein kinase
Linked to g protein Signal proteins
b)IP3, DAG, Ca2+ Second messenger
Chemical Signaling Mechanisms
Medium range intercellular signaling
Hormones via blood
Via air ~
Signaling Pathways:Cell impermeable requires?
Requires receptor in membranes
Signaling Pathways: Cell permeable
Signaling Pathways: cell associated signaling molecules
Signal transduction pathway can amplify the cellular response on an external signal
Hydrophobic will pass through membrane and
do not need receptor
Hydrophylic will not pass
For hydrophobic ligand
also need receptor for proteins
Receptor Types: Channel linked receptors
Receptor Types: Enzyme linked receptors
Protein kinase mostly
Neurotrophin � R
Receptor Types:G protein �
Receptor Types: Intracellular receptors
Activated by cell � permanent signals
G Protein coupled receptors
Metabotropic receptors Requires
Metabotropic receptors: Receptor indirectly controls channel
G protein � gated ion channel
2d messenger systems
Metabotropic receptors: Neuromodulation
Change in sensitivity of neuron
G protein-gated Ion Channels: NT binds to
G protein-gated Ion Channels: NT binds to receptor protein which activates
2d Messenger Systems NT is ?
First Messenger --> Ligand Membrane --> associated componentsReceptorTransductionPrimary effector
G protein binds to channel which does what?
opens or closes
Slower & enduring changes
1 NE � 1000s cAMP
1000s cAMP � 10,000s phosphates
2d Messenger Systems: Effects
Alter properties of receptors
regulation of gene expression ~
protein kinases & phosphatases
Cyclic nucleotides cAMP & cGMP activates?
: protein kinases ~
Increased concentration cyclic AMP activates kinases
The structure and metabolism of cAMP. cAMP is generated by
The enzyme of cAMP is
enzyme adenylyl cyclase
2d messenger: Diacylglycerol
DAG --> protein kinase C (membranes)
2d Messengers: Membrane Lipids
Phoshatidylinositol bisphosphate Cleaved by phosphylipase C
cAMP It is inactivated by hydrolysis of AMP, a reaction catalyzed by
2d MEssenger: Inositol triphosphate
IP3 --> Ca2+ (ER) --> Frees Ca2+ from inside to outside
Diacylglycerol & Inositol triphosphate
Activates DAG ---> Protein kinase C and calcium
IP3 is made from PIP2 as uncommon phospholipid membrane where the enzyme phoapholipase C is acivated. Phosphylipase C cleaves PIP2 into
2 molecules of IP3 and DAG.
Roles of IP3 and DAG as second messengers.
1.Ligand binds to receptor
3.Gq activates phospholipase C that generates IP3 and DAG
Inositol triphosphate is water soluble. Diffusing through the cytosol and binding to a calcium channel known as IP3 receptor.
Then he channel opens releasing calcium to eh cytosol.
Calcium then elicits the desired physiological response.
2d Messenger Targets: Enzymes
2d Messenger Targets:: Protein Kinase
: Ca2+, CAMP, DAG, etc.
2d Messenger Targets: Protein Phosphatases
Activated by Ca2+/Calmodulin
The release of calcium ion and signal processes.
Calcium plays an essential role in regulating cellular function
The concentration of Ca is very low in the cytosol due to the presence of
There are several different ways that various stimuli can increase Ca in cytosol (neurotransmitter, fertilization of animal egg, egg activation etc.)