Membrane Proteins

Question 1

peripheral membrane protein

Answer 1

-Associates to membrane by weak noncovalent bonds
-Protein can sometimes be composed of multiple polypeptides
-Dynamic: recruited and released from the membrane
-Mostly hydrophilic

Roles:
1. Signal Transduction
2. Mechanical support for the membrane
3. Anchor for integral membrane proteins
4. Enzymes

Question 2

Red Blood Cell Peripheral Membrane Proteins

Answer 2

-Network of proteins that gives cell shape

Spectrin: On cytoplasmic side
Allows concavity; support and flexibility.

Question 3

Lipid-anchored proteins

Answer 3

-Proteins that are covalently linked to a lipid molecule
- Outside of the bilayer: extracellular or cytoplasmic side

Question 4

GPI-anchored proteins

Answer 4

Proteins linked to a oligosaccharide which attaches to the PI of the membrane

Glycosyl-Phosphatidylinositol linkage

-extracellular space only

Roles
: cell adhesion, receptors

Question 5

Hydrocarbon Chains

Answer 5

-Embedded in the lipid bilayer
-Cytoplasmic leaflet
-Can face either extracellular or cytoplasmic side.