Chapter 6: 6.3 Membrane Proteins

Question 1

List:

Types of Membrane Proteins

Answer 1

1. Type I
2. Type II
3. Type III
4. Type IV
5. Polytopic

Question 2

Describe:

Type I Membrane Proteins

Answer 2

• N-terminus signal, cleave
• Internal transmembrane sequence, stop sequence
• N-terminus on the inside and C-terminus on the outside

Question 3

Describe:

Type II Membrane Proteins

Answer 3

• Internal start sequence, not cleaved
• N on the outside, C on the inside
• Only one internal transmembrane signal (start)

Question 4

Describe:

Type III Membrane Proteins

Answer 4

• Reverse signal sequence
• N on the outside, C on the inside
• Only one internal transmembrane signal (start)

Question 5

Describe:

Type IV Membrane Proteins

Answer 5

• C-terminus signal, not cleaved
• C inside, N outside

Question 6

Describe:

Polytopic Membrane Proteins

Answer 6

• Multiple transmembrane domains
• Orientation depends on number of start and stop sequences