ION CHANNELS
Presented By-Ashutosh Tambare
Ashwin kolhatkarJayti saparia
Kriti KatyayanRaghuramreddy
Rajan Pandey
OUTLINE• What are ion channels?• Channel structure• Types of Gating in Ion Channels• The sodium-potassium pump• Working of ion channels• Importance of ion channels
WHAT ARE ION
CHANNELS ???
They are porous transmembral proteins which help in regulating
the voltage gradient across the plasma
membrane by allowing ions to diffuse through the
pores down their electrochemical gradients.
Types of Gating in Ion Channels
There are Four Types of Gating Controls -
1. Ligand Gating 2. Phosphorylation
The Sodium-Potassium PumpExtracellular fluid with high concentration of Na+
Cytoplasm with high concentration of K+1
Three Na+ bind to the cytoplasmic side of the protein.
2
Phosphate is transferred from ATP to the protein.
3Phosphorylation changes theshape of theprotein, movingNa+ across themembrane.
4
K+ binds to the protein, causingphosphaterelease.
5Release ofphosphatechanges theshape of theprotein, moving K+ to the cytoplasm.
Na+
ATP ADPP
Na+
P
K+
PK+
+ + + +
- - - -
Vm = Q/C
∆Vm = ∆Q/C
THE LIPID BILAYER ACTS LIKE A CAPACITOR
∆Q must change before
∆Vm can change
CHANGE IN CHARGE SEPARATION ACROSS
MEMBRANE CAPACITANCE IS REQUIRED TO CHANGE MEMBRANE
POTENTIAL
-
--
-
-
-
-
--
- -
-
-
-+
++
+
+
+
+
+
-
-
+
++
++
+
++
IMPORTANCE OF ION CHANNELS
• Mediate the generation, conduction and transmission of electrical signals in the nervous system• Control the release of
neurotransmitters and hormones• Transfer small molecules between
cells (gap junctions)
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