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#pH regulation

5 public questions tagged with this topic.

Membrane Transportation

Which ATPase is involved in pH regulation in lysosomes and vacuoles?

V-class ATPases also called V-type vacuolar H+-ATPases are large multi-subunit rotary pumps related to F-type ATP synthases but functioning as ATP-driven proton pumps rather than ATP synthetic machines. Complex comprises peripheral V1 sector containing eight subunits including A3B3 hexamer that hydrolyzes ATP and membrane integral Vo sector with proteolipid c-ring, subunit a and accessory subunits mediating proton translocation. Hydrolysis-driven rotation of central stalk couples to c-ring rotation within Vo pumping H+ into lumen. In cells V-ATPase localizes to lysosomes, endosomes, vacuoles,

Ref: Forgac, Nat Rev Mol Cell Biol 2007, Vacuolar H+-ATPases; Alberts, 7th ed., Chapter 13 acidification.

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Membrane Transportation

The Na+/H+ exchanger (NHE) plays a key role in:

Na+/H+ exchanger NHE, SLC9 family with isoforms NHE1 widely expressed in plasma membrane and NHE3 in renal and intestinal brush border, plus organellar NHE6-NHE9, exchanges intracellular H+ for extracellular Na+ with one-to-one stoichiometry electroneutrally. It is primary pH regulatory mechanism alongside bicarbonate transporters and V-ATPase. Upon intracellular acidification after metabolism or proton leak, allosteric H+ sensor accelerates Na+ influx driving H+ extrusion alkalinizing cytoplasm. In kidney proximal tubule NHE3 accounts for majority of Na+ and bicarbonate reabsorption, while in

Ref: Orlowski & Grinstein, Pflugers Arch 2004, Na+/H+ exchangers; Wakabayashi et al., Compr Physiol 2013.

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pH and Buffer

Which of the following buffers is most important in human blood?

Phosphate buffer is the scientifically accurate answer to this question. Within the study of pH and Buffer, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of Phosphate buffer directly address what is being asked. Among the other options, Carbonate buffer, Acetate buffer, and Borate buffer do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this to

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 2

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