These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Contributions of lipids and proteins to the surface charge of membranes. An electron microscopy study with cationized and anionized ferritin.
    Author: Burry RW, Wood JG.
    Journal: J Cell Biol; 1979 Sep; 82(3):726-41. PubMed ID: 117015.
    Abstract:
    The surface charge of cultured neurons was investigated with the electron microscope markers anionized ferritin (AF) and cationized ferritin (CF). To determine which membrane components could react with the markers, model reactions were used. Both protein-coated Sepharose beads and lipid vesicles were reacted at physiological pH. Results with these model reactions indicate that the following groups may contribute to the surface charge: acidic groups--the sialic acid of both glycoproteins and gangliosides, the carboxyl group of proteins, and the phosphates of phospholipids; basic groups--the amines of proteins. The effect of chemical fixation on the surface charge was investigated. Glutaraldehyde fixation was shown to increase the charge of neutral proteins but not by a mechanism involving unbound aldehydes. Glutaraldehyde fixation of phospholipid vesicles in the presence of CF showed that amine-containing phospholipids were cross-linked to CF. This cross-linkage was seen with the electron microscope as the clumping of CF and the burying of CF in the membrane. Paraformaldehyde fixation had a lesser effect on the charge of proteins but did react with phospholipids as did glutaraldehyde. It is concluded that at physiological pH: (a) most of the charged proteins and lipids on cell surface can contribute to the membrane surface charge, and (b) the membrane surface charge of cells can be greatly changed by chemical fixation.
    [Abstract] [Full Text] [Related] [New Search]