Mapping the electrostatic profiles of cellular membranes

Anionic phospholipids can confer a net negative charge on biological membranes. This surface charge generates an electric field that serves to recruit extrinsic cationic proteins, can alter the disposition of transmembrane proteins and causes the local accumulation of soluble counterions, altering the local pH and the concentration of physiologically important ions such as calcium. Because the phospholipid compositions of the different organellar membranes vary, their surface charges are similarly expected to diverge. Yet, despite the important functional implications, remarkably little is known about the electrostatic properties of the individual organellar membranes. We therefore designed and implemented approaches to estimate the surface charges of the cytosolic membranes of various organelles in situ in intact cells. Our data indicate that the inner leaflet of the plasma membrane is most negative, with a surface potential of approximately -35 mV, followed by the Golgi complex > lysosomes > mitochondria = peroxisomes > endoplasmic reticulum, in decreasing order.

Automated summary

Anionic phospholipids on biological membranes can affect the electric charge distribution and ion concentration, but little is known about the electrostatic properties of different organellar membranes. Research shows that various organelles have different surface charges, with the inner leaflet of cell membranes being the most negative, while the endoplasmic reticulum has the most positive surface potential.