A D-glucose-sensitive cytochalasin B binding component of cerebral microvessels.
The technique of photoaffinity labelling with [4-3H]cytochalasin B was applied to osmotically lysed cerebral microvessels isolated from sheep brain. Cytochalasin B was photo-incorporated into a membrane protein of average apparent Mr 53,000. Incorporation of cytochalasin B was inhibited by D-glucose, but not by L-glucose, which strongly suggests that the labelled protein is, or is a component of, the glucose transporter of the blood-brain barrier. Investigation of noncovalent [4-3H]cytochalasin B binding to cerebral microvessels by equilibrium dialysis indicated the presence of a single set of high-affinity binding sites with an association constant of 9.8 +/- 1.7 (SE) microM-1. This noncovalent binding was inhibited by D-glucose, with a Ki of 23 mM. These results provide preliminary identification of the glucose transporter of the ovine blood-brain barrier, and reveal both structural and functional similarities to the glucose transport protein of the human erythrocyte.
D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002196:Capillaries / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003571:Cytochalasin B / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D012756:Sheep; D013237:Stereoisomerism
D003571:Cytochalasin B; D005947:Glucose