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29 Cards in this Set
- Front
- Back
What are the four types of cell signals?
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1) neurocrine
2)endocrine 3) paracrine 4) autocrine |
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What occurs in neurocrine signaling?
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neurotransmitters released from neuronal terminals --> synaptic cleft --> other cells
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What occurs in endocrine signaling?
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endocrine organs --> signals synthesized and transported --> xport through blood --> target organs
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What occurs in paracrine signaling?
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Signals from endocrine cells travel very short distances to target organ/cell
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What occurs in autocrine signaling?
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signals are synthesized and released by target cells
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Which cells have the largest range of signaling and which cells have the shortest range?
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Longest range - neurocine/endocrine
shortest range - autocrine |
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What is the range for neurocrine signaling?
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long range or short range
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What is the range for endocrine signaling?
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long range
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What is the range for paracrine signaling?
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short range
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What is the range for autocrine signaling?
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same cell/no range
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What are the two types of ligands?
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Lipophilic
Lipophobic |
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What is the difference between how the two types of ligands enter the cells?
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Lipophilic - recognized by intracellular receptors
Lipophobic- do not directly enter cell, first need to be recognized by plasma membrane receptors |
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What are the four characteristics of ligand binding to receptors?
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high affinity
saturable reversible specific |
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What are the three types of plasma membranes?
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1)ligand gated receptors
2) g protein coupled receptors 3) enzyme linked receptors |
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What are the three membrane bound proteins required for G protein coupled receptors?
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1) receptor
2) G protein 3) effector |
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What are the 4 components of the GPCR?
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1) 7 membrane spanning domains
2) 6 loops (3 intra/3 extra-cellular) 3) Ligand binding N-terminus 4) C-terminus |
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What is the function of the N terminus of the GPCR?
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1)ligand binding
2) exposed to extracellular space |
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What is the function of the C terminus of the GPCR?
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1) exposed to cytosol
2) glycosylation sites for post-translational modification for proper folding and cell-surface expression |
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What are the three main families that G proteins are coupled into?
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A/1
B/2 C/3 |
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What is significant about the A subfamily?
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-largest
-sensory |
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What is significant about the B subfamily?
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-long N terminal
-for peptides |
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WHat is significant about the C family?
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-very long N and C terminal regions
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What is the G protein made out of?
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-heterotrimer with 3 different subunits, α β, γ
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What is the function of the G-protein?
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1)become activated once receptor binds the ligand
2) interact with effector to generate second messenger 3) deactivate and associate with receptor again |
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What is the activation and deactivation cycle of the G protein?
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1) deactivated G protein with α, β, γ subunits with α subunit attached to GDP
2)ligand binds receptor 3)GDP on α subunit is exchanged for GTP 4) α-GTP dissociates from βγ 5) subunits go to interact with effector 6) α intrinsic GTPase hydrolyzes GTP --> α-GDP 7) α-GDP associates with β γ subunits |
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What is typical between all G proteins? What is different?
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-Heterotrimer vs Monomer is different
-Same: all switch between active/inactive state |
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What is the function of the α and βγ subunits of the g proteins?
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-α
1) C terminal interacts with receptor and generates specificity 2)seperates G proteins into 4 groups -βγ interact with N terminus of α subunit |
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Does each effector protein interact with a specific G protein?
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yes
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What are some effector proteins that interact with the GTP-α subunit and βγ subunit?
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adenyl cyclase
phospholipase C cGMP specific phosphodiesterases potassium channels |