Formation of the clathrin coated vesicle

The stalk is surrounded by the protein dynamin, which is responsible for cutting the stalk (GTP dependent), so that free clathrin coated vesicles are formed. Dynamin binds to clathrin in its GDP form, but upon GDP/GTP exchange moves to the stalk where it self-assembles into helical stacks of rings, containing about 20 molecules of dynamin. Apparently then coordinated hydrolysis of GTP to GDP occurs to cut the stalk (thus freeing the CCV) and to release the dynamin-GDP molecules. In Drosophila melanogaster a temperature sensitive mutant of dynamin (shibirets) (jap. for paralysed) is known. At the non-permissive temperature these flies can no longer recycle lipids in their nerve cells, which leads to immotility. This makes it easy to collect affected animals for investigation. In mammals two isoforms of dynamin are known, dynamin-1 occurs only in neurons while dynamin-2 occurs in all cells.

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