Protein Processing

Question 0

What is secreted constitutive?

Answer 0

Albumin and collagen

Question 1

What is constitutive secretion?

Answer 1

Continuous process where proteins are packaged into vesicles and released constantly via exocytosis

Question 2

What is regulated secretion?

Answer 2

Proteins package into vesicles only released when required, a signal binds

Question 3

What is secreted regulated?

Answer 3

Insulin

Question 4

What is the process of secretory protein synthesis?

Answer 4

1. Free ribosomes imitate protein synthesis from mRNA
2. A hydrophobic n terminal signal sequence is created
3. Signal sequence of new protein recognised and binds by SIGNAL RECOGNITION PARTICLE (SRP)
4. Protein synthesis stops
5. GTP- bound SRP directs ribosomes to SRP receptors on cytosolic face of rER
6. SRP dissociates
7. Protein synthesis continues, new polypeptide fed into rER via pores in membrane - this is PEPTIDE TRANSLOCATION COMPLEX
8. Signal sequence removed by signal peptidase once protein synthesised
9. Ribosome dissociates and recycled