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24 Cards in this Set
- Front
- Back
Some ion channels contain beta or gamma subunits, which serve what function? |
Regulate gating of the channels |
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Immunocytochemistry can be used to determine what regarding a binding site on a channel? |
Whether it is inside or outside of the cell |
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One way to explore how gene changes affect the function of ion channels is to compare ion channels from different species; These are known as (blank) channels. |
chimeric |
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What is the minimum possible number of subunits necessary to form the pore of an ion channel? |
Two |
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Ion Channels composed of multiple identical subunits are referred to as what? |
Homo-oligomers |
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Auxilliary subunits do what? |
Modify functional properties of an ion channel; can be either cytoplasmic or membrane bound |
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A common motif in voltage gated cation channels |
A membrane spanning segment containing either lysine or arginine on every third position along the alpha helix |
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What is site directed mutagenenesis |
genetic engineering type which substituents or deletes specific amino acid residues in order to assess their contribution to the overall functionality of the protein |
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Function of exogenous ligand |
A drug or toxin that blocks the binding of the agonist either reversibly or irreversibly OR bias the ion channel towards an open state by binding at a regulatory site |
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Inactivation of voltage gated channels |
1. Refractory period after depolarization to restore voltage to resting state. 2. Some Ca2+ channels inactivate when internal Ca2+ level increases after channel opening, due to the binding of Ca2+ to calmodulin (regulatory protein) |
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All ion channels are? |
Large integral-membrane proteins with a core trans membrane domain that contains a central aqueous pore spanning the entire width of the membrane |
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The channel protein often contains? |
carbohydrate groups attached to its external surface |
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What technique can identify membrane-spanning regions of an ion channel protein |
hydrophobicity plot |
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T/F The same type of channel can have somewhat different properties in different species |
True |
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T/F one can exploit the naturally occuring mutations in channel genes |
True |
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In mechanically activated channels, energy is thought to be transferred through |
The cytoskeleton or changes in tension of the lipid bilayer |
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what is the difference between a hetero-oligomer ion channel and a homo-oliger ion channel? |
hetero-oligomer channel is constructed from different types of subunits and homo oligomer ion channels are constructed from a single type of sub-unit |
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A type of genetic engineering in whcih specific amino acid residues are subsituted or deleted in order to test the roles of different amino acids is refered to as (blank) |
site- directed mutagenesis |
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Each of the four hydrophobis regions in the amino acis sequence of a subunit of the ACh receptor is thought to form a(n) |
alpha-helix (a-helix) |
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T/F- Changes in channel function can be caused by mutations |
True |
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T/F- Our genome contains over 70 genes each for K+ channels and ligand-gated channels |
True |
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What are the characteristics of regions that are likely to be important in maintaining the structure and function of a channel |
high degree of similarity that has been conserved through evolution |
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T/F All exogenous substances affect both the normal gating mechanism and interfere with the transmitter-binding site |
False- some substances do not affect the transmitter-binding site. This indirect effect is found in normal, voltage-gated and stretch-gated channels. |
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T/F The pore forming region of channels is made up of at least two or more subunits. These must be identical. |
False- They can also be different. |