Membrane Proteins and Ion Transport

Proteins embedded into the membrane; span the entire membrane or part of it

Integral Proteins

On surface of membrane

Peripheral Proteins

Types of transport proteins

transporters/carriers, channels

Protein has a conformational change to allow molecule to pass; can go with or against the concentration gradient

Transporters/ Carriers

Protein shape stays the same; allows molecules through following the concentration gradient

Channels

small molecules follow concentration gradient without proteins

simple diffusion

Ions pass through membrane using membrane protein

facilitated diffusion

Facilitated diffusion where ions follow concentration gradient

passive transport

Facilitated diffusion where ions go against the concentration gradient; requires energy

active transport

Uses energy from ATP to pump molecules

primary active transport

Uses the energy of a molecule going along the concentration gradient to transport another molecule with it

secondary active transport

transport a single species across a membrane without energy

uniporter

couple the downhill flow of one species to the uphill flow of another in an opposite direction

antiporter

couple the downhill flow of one species to drive the flow of another in the same direction

symporter

Can charged ions easily pass through the membrane?

No; the need exclusive transport proteins

What types of molecules can pass through a channel?

correct size and charge; needs no energy

How can molecules can pass through a carrier protein?

it must bind to the protein and cause a conformational change; needs energy

Transport proteins that work against concentration gradient

proton pump

How does glucose into cells?

glucose transporter proteins

Gradient of electrochemical potential for an ion to move across a membrane

electrochemical gradient

Ways to move ions across an opposing electrical gradient?

coupled transport; ATP driven pump

couple the flow of one molecule to the flow of another to facilitate movement

coupled transport

hydrolyzes ATP to ADP and uses the energy to pump molecules against the gradient

ATP driven pumps

Na+/K+ pump

3 Na+ out, 2 K+ in

difference in electrical potential between internal and external cell

membrane potential; without it there will be an electrical imbalance

Voltage sensor measures the membrane potential causing channel to open/close

Voltage gated ion channel

ligand binds to the channel causing it to open/close

ligand gated ion channel

physical pressure in shape causes it to open/close

stress gated ion channel

Arachidonic acids is generated by ...

phospholipase A2

Which enzyme converts Arachidonic acid into protasglandins

Prostaglandin H2 synthase

Enzyme that is a peripheral protein bound to the ER with just an alpha helix in the hydrophobic portion

Prostaglandin H2 synthase

Arachidonic acid prefer ... regions

hydrophobic

blocks arachidonic acid from getting to the enzyme by blocking hydrophobic channel; causes conformation change

Aspirin mechanism