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Flashcards in Control of intracellular pH Deck (11)
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1

How do you measure pH using electrodes

Two electrodes are used
Electrode 1 is a normal microelectrode measuring Vm
Electrode 2 has a small amount of proline - a H+ sensitive resin in the tip
This measures the Vm for everything apart from proton movement
1-2 gives the change in voltage due to protons which is = to the change in pH
Calibration of electrodes using pH standards
y = mx + c
y = Voltage, X = pH

2

How do you measure pH using fluorescent indicators

Cell is loaded with an inactive form of a charged molecule
Naturally occurring enzymes cleave the inactive form
Indicator excited with specific wavelength of light and the amount of light emitted at a second wavelength is measured
Fluorescence is pH dependant

3

Define a buffer

A system that modulates the effects of acid or alkali load by reversibly consuming or releasing protons

4

What channel is involved in acid loading and how does it work

Cl-/HCO3- exchanger
Inward movement of chloride ions and the removal of bicarbonate from inside the cell - this leaves behind a proton inside the cell causing acidification

5

What chemical inhibits AE1

DIDS

6

What channel is involved in acid extrusion

Na/H exchanger - Relies on the function of Na/KATPase to create a concentration gradient for Na to move into the cell.

7

What is allosteric modification present in NHE1

Protons other than the one being transported bind to the channel at an allosteric site and produce a conformational change in the channel making it more active than before

8

How do CaM and PKC modulate NHE1

They change the set point of the channel making the exchanger more active at more alkali levels
They bind on the long C-terminus

9

How many transmembrane domains does NHE1 have

12

10

What is a role of NHE1

Found on the basolateral membrane of epithelial cells - linked to cell vol control

11

When is resting pH achieved

When the rate of acid extrusion is equal to that of acid loading