Mesenteronal epithelial cell surface charge of the mosquito, Culex tarsalis Coquillett. Binding of colloidal iron hydroxide, native ferritin and cationized ferritin.

The binding of positive and negative colloids of iron hydroxide, native ferritin and cationic ferritin to the mesenteronal epithelial cell surface of the mosquito, Culex tarsalis, was examined electronmicroscopically. The major anionic groups contributing to the negative character of the microvillar surface appear to be the gamma-carboxyls of aspartic and glutamic acids with some contribution from uronic acids. These same anionic groups are expressed along the basolateral membranes and the basal lamina along with the much more acidic sulfates. These specific groups were implicated through an evaluation of the binding of our surface probes at various pH's from 0.8 through 7.2.