BCH210 - Week 5 Questions With
Complete Solutions
What are the three types of membrane proteins? correct answer:
1) Peripheral
2) Integral
3) Lipid anchored
What are peripheral membrane proteins? correct answer: -
Adhere to surface of lipid membranes or integral membrane
proteins through non-covalent interactions
- Can be removed using milder conditions
What is the signature amino acid sequence for amphipathic
helices? correct answer: P-P-NP-NP-P-P-NP-NP
alternating polar and non-polar aa
What are integral membrane proteins? correct answer: -
proteins that pass all the way through the membrane
- Require harsh conditions for purification (strong detergents or
organic solvents)
What is type 1 TM protein? correct answer: Single pass, NH3 +
outside
What is type 2 TM protein? correct answer: Single pass, NH3 +
inside
, What is type 3 TM protein? correct answer: Multi-pass (single
polypeptide)
What is type 4 TM protein? correct answer: Multiple
polypeptides, fourth degree structure
What is type 5 TM protein? correct answer: single lipid anchor
What is type 6 TM protein? correct answer: TMs + lipid anchor
What are lipid anchored proteins? correct answer: - Lipid chains
are covalently attached to amino acid functional groups and side
chains
- Require harsh detergents or solvents for membrane removal
GPI-anchored proteins correct answer: Are covalently linked
through a sugar chain and lipid anchor (GPI = glycosyl
phosphatidylinositol)
How do you purify membrane proteins? correct answer: - Some
membrane proteins can be removed using milder conditions to
disrupt non covalent interactions, while others need stronger
conditions to replace the lipids and disrupt hydrophobic
interactions
- Detergents create micelles around hydrophobic regions to
solubilize all membrane proteins
- Detergents are amphipathic molecules that can help form
micelles around the hydrophobic regions of a membrane protein,
helping with solubilization.
Complete Solutions
What are the three types of membrane proteins? correct answer:
1) Peripheral
2) Integral
3) Lipid anchored
What are peripheral membrane proteins? correct answer: -
Adhere to surface of lipid membranes or integral membrane
proteins through non-covalent interactions
- Can be removed using milder conditions
What is the signature amino acid sequence for amphipathic
helices? correct answer: P-P-NP-NP-P-P-NP-NP
alternating polar and non-polar aa
What are integral membrane proteins? correct answer: -
proteins that pass all the way through the membrane
- Require harsh conditions for purification (strong detergents or
organic solvents)
What is type 1 TM protein? correct answer: Single pass, NH3 +
outside
What is type 2 TM protein? correct answer: Single pass, NH3 +
inside
, What is type 3 TM protein? correct answer: Multi-pass (single
polypeptide)
What is type 4 TM protein? correct answer: Multiple
polypeptides, fourth degree structure
What is type 5 TM protein? correct answer: single lipid anchor
What is type 6 TM protein? correct answer: TMs + lipid anchor
What are lipid anchored proteins? correct answer: - Lipid chains
are covalently attached to amino acid functional groups and side
chains
- Require harsh detergents or solvents for membrane removal
GPI-anchored proteins correct answer: Are covalently linked
through a sugar chain and lipid anchor (GPI = glycosyl
phosphatidylinositol)
How do you purify membrane proteins? correct answer: - Some
membrane proteins can be removed using milder conditions to
disrupt non covalent interactions, while others need stronger
conditions to replace the lipids and disrupt hydrophobic
interactions
- Detergents create micelles around hydrophobic regions to
solubilize all membrane proteins
- Detergents are amphipathic molecules that can help form
micelles around the hydrophobic regions of a membrane protein,
helping with solubilization.
