Identification and Characterization of the Glucose Transporter of the Blood-Brain Barrier by Cytochalasin B Binding and Immunological Reactivity

• Published in: Proceedings of the National Academy of Sciences - PNAS 1984-11, Vol.81 (22), p.7233-7237
• Main Authors: Arthur P. K. Dick, Harik, Sami I., Klip, Amira, Walker, Denise M.
• Format: Article
• Language: English
• Subjects: Animals; Antiserum; Binding sites; Blood-Brain Barrier; Carrier Proteins - immunology; Carrier Proteins - isolation & purification; Carrier Proteins - metabolism; Cerebral cortex; Cerebral Cortex - analysis; Cerebrovascular Circulation; Cytochalasin B - metabolism; Cytochalasins; Deoxyglucose - metabolism; Erythrocyte membrane; Erythrocytes; Facilitative glucose transport proteins; gamma-Glutamyltransferase - metabolism; Glucose - metabolism; Hexoses; Male; Microvessels; Molecular Weight; Monosaccharide Transport Proteins; Particulate matter; Rats; Rats, Inbred Strains; Subcellular Fractions - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.81.22.7233

[3H]Cytochalasin B was used as a ligand to identify and characterize the glucose transporter in cerebral microvessels of the rat and the pig. Specific cytochalasin B binding, defined as that fraction of the total binding that is stereospecifically displaced by excess (500 mM) D-glucose, is saturable. Kinetic studies of this specific binding to cerebral microvessel preparations showed a dissociation constant (Kd) of 0.65-0.88 μ M and a maximal binding (Bmax) of 60-80 pmol/mg of protein. In comparison, the Bmaxof particulate fractions of the cerebral cortex was about one-tenth that of cerebral microvessels. The ability of various hexoses to displace specific cytochalasin B binding to cerebral microvessels in vitro correlated well with the capability of these hexoses to cross the blood-brain barrier in vivo. Irreversible photoaffinity labeling of the glucose transporter of cerebral microvessels with cytochalasin B followed by solubilization and polyacrylamide gel electrophoresis labeled a polypeptide(s) with a molecular weight of about 53,000. Antibodies prepared against the glucose transporter of human erythrocytes also reacted with a polypeptide(s) with a molecular weight of about 53,000 on electrophoresed preparations of cerebral microvessels. These results indicate that cerebral microvessels are richly endowed with a glucose transporter moiety of similar molecular weight and antigenic characteristics as the glucose transporter of human erythrocytes and other mammalian tissues.