protein transport

Question 1

what is the purpose of retrograde transport?

Answer 1

a mechanism for ensuring that the correct proteins are present in the right golgi cisternae

Question 2

in which direction do proteins pass through the golgi?

Answer 2

cis-medial-trans

Question 3

what is co-translational transport?

Answer 3

where proteins are transported as translation occurs

Question 4

how can labelling experiments show that secretory proteins are localised to the ER lumen shortly after synthesis?

Answer 4

1) cells are briefly incubated with radiolabelled amino acids
2) cells homogenised, plasma membrane fractured and rER sheared into microsomes
3) microsomes are treated with a protease, with or without a detergent present
4) digestion of secretory proteins only in the presence of detergent provides evidence that new proteins are located in the membrane of the microsome

Question 5

why are pancreatic exocrine cells used as a medium for experiments on protein transfer?

Answer 5

the cells contain much ER, as the cells are specialised to produce a lot of secretory proteins in the form of enzymes