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41 Cards in this Set
- Front
- Back
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synthesis of cAMP by
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adenylate cyclase
-rapidly catalyzes cAMP synthesis from ATP |
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cAMP is rapidly hydrolyzed back to AMP by
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cAMP phophodiesterase
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cAMP-dependent Protein Kinase (PKA) mediates ____
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most of the effects of cAMP
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PKA protein kinase is made of
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4 different subunits
with 2 regulatory subunits |
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type 1 is in the
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cytosol
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type II is
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bound via special anchoring proteins to PM, NM, mitochondrial OM, and MT
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in all cases all types move to ____
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nucleus upon activation. once there, catalytic subunits phosphorylate gene regulatory proteins
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gene transcription is activated by a
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rise in cyclic AMP concentration
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beta-adgeneric receptor is a ___
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g-signal protein receptor responsible for changes in response to stress
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3 types of inositol phospholipids
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phosphatidylinositol
PI 4-phosphate PI 4,5 biphosphate |
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some G-proteins activate the IP signaling pathway
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phospholipase
c-beta activation |
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the generation of second messengers
steps 1-3 |
generation of PI
generation of PIP generation of PIP2 |
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PIP2 is present in ____ amounts and ____ is crucial
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small amounts but breakdown is crucial
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The hydrolysis of PI(4,5)P2 by
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phopholipase c-beta
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in step 2 PIP2 goes to
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DAG which activates protein kinase
and IP3 (inositol 1,4,5-trisphosphate) which releases calcium from the ER |
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termination of initial ca2+ response?
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?
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how many branches are there of the inositol phospholipid pathway
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2
what are they? |
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ca2+ functions as a ___
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ubiquitous intracellular messenger
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generation of IP3 is coupled to ____
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calcium release from ER
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the 3 steps of generation of IP3 are 1.
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IP3 rapidly diffuses from the PM thru the cytosol binds to IP3-gated calcium release channels present in the ER
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step 1 proceeds to step 2 to generate
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an autocatalytic, self-propagating stimulation of calcium release
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the response is ____
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quelled upon the dephosphorylation of IP3 by a specific phosphatase and the reduction of cytosolic calcium by calcium-dependent pumps in the ER and PM
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there are 3 types of ca2+ channels which mediate this ca2+ channels signaling
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voltage-gated (membrane depolarizing)
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2
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IP3-gated, g-protein mediated
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3
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ryanodine-gated (react to changes in PM potential and release ca2+ from the SR, thereby stimulating the contraction of muscle cells)
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what are the main way eukaryotic cells maintain a verry low concentration of free ca2+ tightly
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actively pumped out of cytosol
pumped into ER or mitochondria molecules in cell bind free ca2+ |
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calmodulin
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a ubiquitous regulator of ca2+ dependent processes (multipurpose intracellular Ca2+ receptor)
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calmodulin is a small
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(17kD) soluble protein, present in all eukaryotic cells
-1% of the cellular protein -highly conserved from yeast to humans -mediates a variety of Ca2+ regulated processes |
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calmodulin contains 4 high ___
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affinity ca2+ binding sites
undergoes conformational change when Ca2+ binds -binds various target enzymes to allosterically activate |
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CaM-kinases mediate many of
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the actions of ca2+ in animal cells
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binding of the 4 sites in animal cells
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binds inhibitory region which changes shape, become activated, able to take phosphate available from ATP and phosphorylate itself (helps molecule remember its conformation)
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rhodopsin is a
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g-transducin
-has to do with vision and also smell regulate c-n-g Ion Channels |
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light to rhodopsin -->
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g-transducin --> activates cGMP Phosphodiesterase --> decrease in cGMP
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Light to rhodopsin is an
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ion channel regulated by cNT
-smell and vision depend on G-protein linked receptors that regulate cyclic-nucleotide-gated Ion Channels |
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smell
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10,000 G increase cAMP
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vision
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fastest g-protein mediated response, light
decrease in cGMP |
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what phosphorylates Rhodopsin?
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RK
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arrestin sequesters
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physically blocks from interacting with it
-keeps it in off position (something with phosphorylation) -acts as an adaptor, helps make clathrin coated pit |
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g-protein linked receptor kinases (GRKs) and arrestins in receptor
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desensitization
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GRK phosphorylates
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activated receptor at multiple sites
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arrestin binds to
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phosphorylated receptor
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