GPCRs: Defining Structural Features
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-7-Transmembrane (7TM) Receptor with Ligand Binding Domain
-Associated with Heterotrimeric G Protein
Describe how large proteins are transported across the plasma membrane.
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Large proteins are transported across the plasma membrane via
membrane-mediated transport. This includes endocytosis (in) or exocytosis
(out). A piece of the plasma membrane surrounds the protein and pinches
off (forms a vesicle).
,Define CICR and indicate the types of muscle cells in which it is required for
contraction
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Calcium Induced Calcium Release is used in Cardiac muscles. Ca++ binds to
Ca++-Gated Ryanodine Receptors to OPEN them; this releases a lot of Ca++
that was sequestered in the SR. The physiological agonist is Ca++ and the
non-physiological agonist is Ryanodine.
Multi Unit Smooth Muscle
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Each cell receives neural input. Each muscle cell may contract
independently of its neighbor, capable of fine control. (ex: iris in eye).
Explain how GPCRs contribute to salivary secretion.
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GPCRs are used to draw amylase into the lumen. To create saliva. GPCRS
are also used t the Muscarinic ACh receptor (Gq), which leads to the
generation of IP3, DAG, and CA++ release from the ER which helps creates
the isotonic saliva solution.
Draw the Action Potential. Identify each phase of the Action Potential and explain
how ion movement causes it. Be sure to identify the names and states of any
,important ion channels in this process.
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Resting: Voltage Gated Na+ channels are closed, Voltage Gated K+
channels are closed, mostly K+ leak channels and a few Na+ leak channels
are open)
Depolarization to Threshold: A stimulus (EPSP), or a graded potential from
Na+ spreading from previous patch of axon membrane
Depolarization Phase: All the V-Gated Na Channels open, permitting Na+
into the cell. Voltage K+ channels still remain closed, leak channels are
always open but are drowned out by Na+ coming from the Voltage Gated
Na+ Channels.
Repolarization Phase: Prolonged depolarization causes Voltage Gated Na+
Channels to inactivate so no Na+ comes into cell. The Voltage Gated K+
channels open, K+ leaves the cell.
Hyperpolarization Phase: Voltage Gated Na+ channels are reset and
closed. Voltage K+ channels are slow to close, some still open so some K+
are still leaving the cell.
Contrast Ionotropic and Metabotropic receptors on the postsynaptic neuron. List an
example of each kind of receptor and how ligand binding to it would modify the
postsynaptic neuron.
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Ionotropic: Ligand-gated Ion Channels; transmitter binding changes
receptor conformation and cause the channel to open. Example: Nicotinic
ACh Receptor
Metabotropic: Ligand-Gated Receptors that are separate from the ion
channels they affect; they are often GPCRs and and promote long lasting
changes in the neuron (gene transcription/activity). They regulate second
messengers or activate protein kinases. Example: Muscarinic ACh Receptor
, Kinases: Defining Structural Features
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-2 Identical proteins that bind ligand, pass through membrane
-Intracellular Domain with Tyrosines (that can be Phosphorylated)
Compare Temporal Summation and Spatial Summation in terms of the number of
presynaptic neuronal inputs and their rate of action potential firing.
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-Temporal Summation: One presynaptic neuron fires in rapid succession, so
the post synaptic neuron receives successive PSPS spaced a bit apart
-Spatial Summation: Many presynaptic neurons fire at the same time, so the
post synaptic neuron receives many PSPs simultaneously
Explain how the same ligand can promote different effects on different cells. Reason
through how this works for the ligand ACh.
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The same ligand can promote different effects on different cells because
the receptors may have different internal structures that result in a different
intracellular response. For example, ACh is able to bind to Nicotinic and
Metabotropic ACh receptors.
Gi-GPCR pathway
Give this one a try later!
-7-Transmembrane (7TM) Receptor with Ligand Binding Domain
-Associated with Heterotrimeric G Protein
Describe how large proteins are transported across the plasma membrane.
Give this one a try later!
Large proteins are transported across the plasma membrane via
membrane-mediated transport. This includes endocytosis (in) or exocytosis
(out). A piece of the plasma membrane surrounds the protein and pinches
off (forms a vesicle).
,Define CICR and indicate the types of muscle cells in which it is required for
contraction
Give this one a try later!
Calcium Induced Calcium Release is used in Cardiac muscles. Ca++ binds to
Ca++-Gated Ryanodine Receptors to OPEN them; this releases a lot of Ca++
that was sequestered in the SR. The physiological agonist is Ca++ and the
non-physiological agonist is Ryanodine.
Multi Unit Smooth Muscle
Give this one a try later!
Each cell receives neural input. Each muscle cell may contract
independently of its neighbor, capable of fine control. (ex: iris in eye).
Explain how GPCRs contribute to salivary secretion.
Give this one a try later!
GPCRs are used to draw amylase into the lumen. To create saliva. GPCRS
are also used t the Muscarinic ACh receptor (Gq), which leads to the
generation of IP3, DAG, and CA++ release from the ER which helps creates
the isotonic saliva solution.
Draw the Action Potential. Identify each phase of the Action Potential and explain
how ion movement causes it. Be sure to identify the names and states of any
,important ion channels in this process.
Give this one a try later!
Resting: Voltage Gated Na+ channels are closed, Voltage Gated K+
channels are closed, mostly K+ leak channels and a few Na+ leak channels
are open)
Depolarization to Threshold: A stimulus (EPSP), or a graded potential from
Na+ spreading from previous patch of axon membrane
Depolarization Phase: All the V-Gated Na Channels open, permitting Na+
into the cell. Voltage K+ channels still remain closed, leak channels are
always open but are drowned out by Na+ coming from the Voltage Gated
Na+ Channels.
Repolarization Phase: Prolonged depolarization causes Voltage Gated Na+
Channels to inactivate so no Na+ comes into cell. The Voltage Gated K+
channels open, K+ leaves the cell.
Hyperpolarization Phase: Voltage Gated Na+ channels are reset and
closed. Voltage K+ channels are slow to close, some still open so some K+
are still leaving the cell.
Contrast Ionotropic and Metabotropic receptors on the postsynaptic neuron. List an
example of each kind of receptor and how ligand binding to it would modify the
postsynaptic neuron.
Give this one a try later!
Ionotropic: Ligand-gated Ion Channels; transmitter binding changes
receptor conformation and cause the channel to open. Example: Nicotinic
ACh Receptor
Metabotropic: Ligand-Gated Receptors that are separate from the ion
channels they affect; they are often GPCRs and and promote long lasting
changes in the neuron (gene transcription/activity). They regulate second
messengers or activate protein kinases. Example: Muscarinic ACh Receptor
, Kinases: Defining Structural Features
Give this one a try later!
-2 Identical proteins that bind ligand, pass through membrane
-Intracellular Domain with Tyrosines (that can be Phosphorylated)
Compare Temporal Summation and Spatial Summation in terms of the number of
presynaptic neuronal inputs and their rate of action potential firing.
Give this one a try later!
-Temporal Summation: One presynaptic neuron fires in rapid succession, so
the post synaptic neuron receives successive PSPS spaced a bit apart
-Spatial Summation: Many presynaptic neurons fire at the same time, so the
post synaptic neuron receives many PSPs simultaneously
Explain how the same ligand can promote different effects on different cells. Reason
through how this works for the ligand ACh.
Give this one a try later!
The same ligand can promote different effects on different cells because
the receptors may have different internal structures that result in a different
intracellular response. For example, ACh is able to bind to Nicotinic and
Metabotropic ACh receptors.
Gi-GPCR pathway
