ATPase Pumps

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Within Active transport there are three different types of ubiquitous ATPase pumps found in all cell types. Their main function is to pump small molecules across small membranes, achieved through the Hydrolysis of ATP to ADP and Pi which releases energy driving the passage of molecules across the membrane. The three types of pump are:

  1. P-type pumps: P-type pumps are transmembrane proteins and are so called as they phosphorylate themselves during the pump cycle. They are laregly responsible for maintaining the concentration gradient of ions such as Na+ and K+ across cell membranes.
  2. F-type pumps: These pumps are turbine shaped and are made up of many different subunits. They differ structurally from P-type pumps and are found in the plasma membrane of bacteria and the inner membrane of Mitochondria. They work in reverse compared to the other pumps as the H+ gradient is used to drive the synthesis of ATP from ADP and Pi and so are referred to as ATP synthases. V-Type ATPases, for example, use the energy from the hydrolysis of ATP to set up a concentration gradient of H+ through a proton pump. This movement of H+ ions allows for acidification that is essential in many biological processes. In the kidney for example, V-type ATPases in the late distal convoluted tubule power the active transport of H+ into the urine across epithelial cells. This results in the urine remaining sufficiently acidic and in turn, prevents subsequent disorders, such as renal tubule acidosis, from occurring[1].
  3. ABC transporters: ABC transporters differ as unlike the other pumps which only selectively pump ions, they also pump other small uncharged moleules[2].

References

  1. NCBI. Regulation and Isoform function of the V-ATPases. 2015 [cited 18/11/18]; Available from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2907102/
  2. Alberts, A., Johnson, A., Lewis, J., Raff, M., Roberts, K., and Walter, P. (2008) Molecular Biology of the Cell, fifth edition, New York: Garland Science.
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