BIO 365R lecture 6

BIO 365R lecture 6 - Patch Clamping can record current...

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Patch Clamping can record current passing through An individual ion channel
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Inventors of the patch clamp Erwin Neher (1944- Bert Sakmann (1942- Nobel prize 1991
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Record from a patch many times. Average the responses. Compare with the current recorded from the whole cell. The G-V curve is a curve of the probability of channel opening vs voltage.
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Hodgkin & Huxley (1952) g K = g K(max) n 4 g Na = g Na(max) m 3 h
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Relationship between gating current and ionic current: estimates of ~3-4 charges/channel subunit.
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Gating current is greater and faster at more depolarized voltages.
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Molecular structure of a K + leak channel M1 and M2 are membrane spanning helices that line the inner channel, P is the pore loop that dips into the membrane and forms the pore. The P loop determines the kind of ion that can enter the channel.
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K + channel subunits form a tetramer around a pore. M1 M2 M2 M1 M2 M1 M1 M2 Side view of two subunits facing each other Top view of four subunits
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Structure of voltage- dependent channels 4 subunits form tetramer Single protein forms channel
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Voltage-dependent K + channel subunits also tetramerize. S5 S6 S6 S5 S6 S5 S5 S6 S2 S4 S3 S1 S4 S3 S2 S1 S4 S3 S2 S1 S4 S3 S2 S1
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Voltage-dependent Na + and Ca2+ channels are one long protein. S5 S6 S6 S5 S6 S5 S5 S6 S2 S4 S3 S1 S4 S3 S2 S1 S4 S3 S2 S1 S4 S3 S2 S1
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Structure of voltage-gated K + channels + S1 S2 S3 S4 S6 S5 + + H 3 N CO 2 - P loop or Pore loop
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DIII S4
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This note was uploaded on 04/12/2009 for the course BIO 51340 taught by Professor Zakon during the Spring '09 term at University of Texas.

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BIO 365R lecture 6 - Patch Clamping can record current...

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