Intracellular pH

[3] The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those that are dependent and those that are independent of the concentration of bicarbonate (HCO−3).

Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pHi of 6.8–7.1).

[3] These sensors can permit H+ to pass through the cell membrane accordingly, allowing for pHi to be interrelated with extracellular pH in this respect.

Since the proteins have acidic and basic regions, they can serve as both proton donors or acceptors in order to maintain a relatively stable intracellular pH.

[15] Since these are both degradative organelles that engulf and break down other substances, they require high internal acidity in order to successfully perform their intended function.

[18][19] For measuring pH inside of organelles, a technique utilizing pH-sensitive green fluorescent proteins (GFPs) may be used.

[24] To determine the pH inside organelles, pH-sensitive GFPs are often used as part of a noninvasive and effective technique.

[20] By using cDNA as a template along with the appropriate primers, the GFP gene can be expressed in the cytosol, and the proteins produced can target specific regions within the cell, such as the mitochondria, golgi apparatus, cytoplasm, and endoplasmic reticulum.