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ATPase in question

In respects to this certain ATPase transporter. What do i look for in respects to determining what specific kind it is out of:

  • F-ATPases
  • V-ATPases
  • A-ATPases
  • P-ATPases
  • E-ATPases

Im assuming that analyzation of the gradients dealt with will guide me to the answer. With that logic, i can assume that this is an F-ATPase since i know this membrane protein can synthesize ATP using a H+ gradient, and work in the reverse to create a H+ gradient using the energy gained from the hydrolysis of ATP.( I see 2H+ cations being expelled) Is this a correct method in differentiating ATPases ?

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  • $\begingroup$ Can you please rephrase your question, as I don't understand it? You want to know if you identified the ATPase in the image as the F0-ATPase? Or do you want to know what is different between the different subtypes? $\endgroup$
    – Chris
    Sep 19, 2014 at 20:41
  • $\begingroup$ Sorry for the confusion. My question is, am I going about determining what sort of ATPase this is in the correct way? I determined that this photo depicts a F-ATPase by analyzing the 2H+ cations going through it. And is this an F-ATPase at all? You seem to be "the guy" in molec bio, I appreciate it. $\endgroup$
    – Macedon93
    Sep 19, 2014 at 22:11

1 Answer 1

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First of all, I think you need to research the subunit structures of the various ATPase classes in the list because I am pretty sure that several of them are not as complex as this.

Although this superficially looks like the F-ATPase responsible for synthesising ATP by using the proton gradient generated by the electron chain, there is a clue in that diagram that this may actually be a V-ATPase. The V-ATPases use ATP hydrolysis to move protons from the cytoplasm into the lumen of acidic organelles like lysosomes. The diagram in the question depicts a process like that (ATP is being hydrolysed). Now, you can drive the F ATPase in reverse to achieve this situation, so that isn't definitive.

The labelling of the two compartments is also consistent with the idea that it is a V-ATPase since 'lumen' isn't a word that is usually used in the context of the mitochondrion (it would normally be 'matrix').

So I would suggest that you find out if the subunit labelling is like that used in F-ATPase or V-ATPase (or both). A Google image search will help you to find cartoons of ATPases.

My guess, before doing the suggested research, is that this is a V-ATPAse.

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  • $\begingroup$ I think that, too. Have a look at the direction in which the ATPase is working, this should give the final clue. It pumps from the cytosol into the lumen. $\endgroup$
    – Chris
    Sep 20, 2014 at 7:18
  • $\begingroup$ Yes, but as I said in my answer, you can artificially get F-ATPase to do that, although probably not in the context of cellular compartments. $\endgroup$
    – Alan Boyd
    Sep 20, 2014 at 7:24
  • $\begingroup$ The F-ATPases are locared in the inner mitochondrial membrane and are not in contact with the cytoplasm if I remember correct. $\endgroup$
    – Chris
    Sep 20, 2014 at 9:07
  • $\begingroup$ Thank you for the insight. With further research i've found that this is indeed a V-ATPase.(Learning that the V stands for Vacuole surely helps). Also, V-ATPases hydrolyze, ATP which is clearly seen in the illustration. While F-ATPases only synthesize ATP using a H+ gradient. $\endgroup$
    – Macedon93
    Sep 20, 2014 at 18:27
  • $\begingroup$ bio.davidson.edu/courses/molbio/molstudents/spring2010/sween/… $\endgroup$
    – Macedon93
    Sep 20, 2014 at 18:28

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