1. Ion Channels in the Plasma Membrane of Pollen Tube Presented by Xia Fan

2. Introduction What Are Ion Channels: What Are Ion Channels: They are pore-forming proteins that help establish the small voltage gradient that exists across the membrane of all living cells, by controlling the flow of ions. They are pore-forming proteins that help establish the small voltage gradient that exists across the membrane of all living cells, by controlling the flow of ions. Archetypal channel pore is just one or two atoms wide at its narrowest point. It conducts a specific species of ion and conveys them through the membrane single file--nearly as fast as the ions move through free fluid. In some ion channels, access to the pore is governed by a "gate," which may be opened or closed by chemical or electrical signals, or mechanical force, depending on the variety of channel. Archetypal channel pore is just one or two atoms wide at its narrowest point. It conducts a specific species of ion and conveys them through the membrane single file--nearly as fast as the ions move through free fluid. In some ion channels, access to the pore is governed by a "gate," which may be opened or closed by chemical or electrical signals, or mechanical force, depending on the variety of channel.

3. Different Types of Ion Channels: Different Types of Ion Channels: Voltage-gated channels open or close, depending on the transmembrane potential. Voltage-gated channels open or close, depending on the transmembrane potential. Stretch-activated channels open their pores in response to mechanical deformation of the plasma membrane. Though little is known about these channels, they may be linked to molecules in the cytoskeleton, which may open them by transmitting physical forces of stretch or pressure to the channels, causing them to undergo a conformational change. The channels may also be pulled open due to tension on the membrane itself. Opening the channels allows ions to which they are permeable to flow down their electrochemical gradients into or out of the cell, causing a change in membrane potential. Stretch-activated channels open their pores in response to mechanical deformation of the plasma membrane. Though little is known about these channels, they may be linked to molecules in the cytoskeleton, which may open them by transmitting physical forces of stretch or pressure to the channels, causing them to undergo a conformational change. The channels may also be pulled open due to tension on the membrane itself. Opening the channels allows ions to which they are permeable to flow down their electrochemical gradients into or out of the cell, causing a change in membrane potential.

4. Identification and Characterization of SA Ion Channels in Pollen Protoplasts Result Result SA Ca2+ channels are identified in pollen grain and tube tip protoplasts, with similar but not identical properties. These channels were localized to a small region of the grain protoplasts associated with the site of tube germination. SA Ca2+ channels are identified in pollen grain and tube tip protoplasts, with similar but not identical properties. These channels were localized to a small region of the grain protoplasts associated with the site of tube germination. SA K+ and spontaneous K+ channel are identified in pollen grain and they are distributed over the entire grain surface, but neither was present at the germination site or at the tip. SA K+ and spontaneous K+ channel are identified in pollen grain and they are distributed over the entire grain surface, but neither was present at the germination site or at the tip. Neither SA channel was detected in the grain protoplasts unless the grains were left in germination medium for at least 1 h. Neither SA channel was detected in the grain protoplasts unless the grains were left in germination medium for at least 1 h.

5. Spontaneous K+ Channels in Grain Protoplasts