Question

In the process of intracellular membrane vesicle transport in Eukaryotes neither the formation of such transport vesicles nor their fusion with a target membrane occur spontaneously in the cell. Briefly describe the machinery that cells use to achieve these two processes

Answer 1

Ans . Formation of transport vesicle :-

Many vesicles are made in the Golgi apparatus and the endoplasmic reticulum, or are made from parts of the cell membrane by endocytosis.

Cells ingest fluid , molecules and particles by endocytosis, in which localized regions of the plasma membrane invaginate and pinch off to form endocytic vesicles. As a result , they and their ligands are efficiently internalized in clathrin- coated vesicles, a process called receptor-mediated endocytosis.

Fusion of transport vesicles with target membrane occurs in following series of events :-

1) Specification of the vesicle delivery site

2) the recruitment of components capable of initiating vesicle 'capture'

3) the formation of a bridge between the vesicle and the target membrane

4) conformational change that allows the vesicle and target membrane proteins to come close enough to interact

5) dissociation of the tethering proteins( transport protein particles) , to free them for another round of transport.