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Everybody seems to agree that endocytosis is an energy-using process, and as such requires ATP hydrolysis. However, which particular step requires it? More precisely, which 'molecular machine' involved in endocytosis requires ATP? I cannot seem to find a good answer in the literature.

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    $\begingroup$ Endocytosis can happen through several processes, such as clathrin coated pits or caveolae. Do you have one or the other in mind? $\endgroup$ – user137 Jul 20 '15 at 16:13
  • $\begingroup$ Sorry, yes, I was mainly thinking about clathrin-mediated endocytosis. We can focus on that one. $\endgroup$ – m3tro Jul 20 '15 at 16:29
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Endocytosis (specifically you asked about clathrin-mediated endocytosis) is indeed an energy consuming process. the coating of the vesicle may be "spontaneous", but the pinching off of the vesicle, the uncoating of the clathrin, and the transportaion of the vasicle inside the cell all require ATP/GTP hydrolysis.

Dynamin - dynamin forms a spiral around the neck of the vesicle, and uses GTP hydrolysis which in order tighten the coil around the vesicle neck causes it to break and results in the pinching off of the vesicle from the parent membrane.

The uncoating of the clathrin is also ATP/GTP consuming. proteins such as hsp70 chaperon and auxilin is thought to be involved in the ATP hydrolysis. the uncoating process starts after the pinching off of the vesicle.

the tranportation of the vesicle will also cost energy, proteins such as the Myosin family are considered to transport endocytic vesicles into the cell, and use ATP hydrolysis.

Dynamin - Wiki

Myosin - Wiki

Uncoating process - Molecular Biology Of The Cell ed.6 p.701

Dynamin - Molecular Biology Of The Cell

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  • $\begingroup$ Thank you for your answer. I asked this a while ago... Eventually I got a similar answer to yours on Reddit. It seems clear that energy is required for pinch-off and later processes, but perhaps the previous steps can occur spontaneously. $\endgroup$ – m3tro Jan 26 '16 at 16:42

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