341lecture21oct28sakai

341lecture21oct28sakai - Cell Biology 341 Last lecture Weds...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Cell Biology 341 Weds., October 28, 2009 Today: Voltage-gated channels in neurons open in response to changes in membrane potential A ligand-gated channel that opens in response to a neurotransmitter Last lecture: ABC transporters are pumps that use ATP to actively transport small molecules Channel proteins carry out passive transport: They are highly selective, and may be ligand-gated, voltage-gated or mechanically-gated Structure of a K + channel: selectivity filter K + leak channels create a negative membrane potential across the plasma membrane Aquaporins are specific for water transport The aquaporin channel has a hydrophobic side to prevent ion transport
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Aquaporins are channel proteins that transport water, but not ions One side of the pore is lined with hydrophilic groups, including (C=O), that interact with water molecules moving through the pore in single file The other side is lined with hydrophobic residues (yellow) that cannot interact with ions Thus the channel only transports water Figure 11-27 Aquaporin is a tetramer of 4 subunits, each containing a pore (one shown) H + is not transported because 2 asparagine side chains bind the oxygen of the central water in line an H + relay H + relay is blocked
Background image of page 2
Neurons use changes in the membrane potential across the plasma membrane to convey signals Dendrites receive signals from other
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

341lecture21oct28sakai - Cell Biology 341 Last lecture Weds...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online