Lecture 6.1: Protein Sorting

Question 1

What is required for protein sorting? (4)

Answer 1

• A signal (address), intrinsic to the protein
• A receptor that recognises the signal and
  which directs it to the correct membrane
• A translocation machinery
• Energy to transfer the protein to its new
  place

Question 2

Functions of the Endoplasmic Reticulum (7)

Answer 2

• Insertion of proteins into membranes
• Specific proteolytic cleavage
• Glycosylation
• Formation of S-S bonds
• Proper folding of proteins
• Assembly of multisubunit proteins
• Hydroxylation of selected Lys and Pro
  residues

Question 3

Why is glycosylation of proteins important? (4)

Answer 3

• Correct protein folding
• Protein stability
• Facilitates interactions with other molecules
• Deficiencies in N-linked glycosylation lead to
  severe inherited human disease: Congenital
  disorders of glycosylation (CDG)