Properties of a synaptic vesicle protein binding plasma membranes.
Synaptic vesicles contain a protein (agglutinin) which binds cell plasma membranes. The protein activity is titrated measuring the agglutination of rabbit trypsinized-fixed red blood cells induced by serial dilutions of purified vesicles. The protein is highly concentrated in vesicles: the specific activity is 150-fold higher in vesicles compared to the brain homogenate, and 20-fold higher compared to the crude synaptosomal membrane fraction. The binding is specifically inhibited by the four major brain sialoglycosphingolipids, with a higher affinity for polysialo- rather than for monosialoganglioside (GM1) IC50 are 3.9 x 10(-5) M (GT1b), 8.9 x 10(-5) M (GD1a), 2.8 x 10(-4) M (GD1b) and 4.9 x 10(-4) M (GM1). Cells which are not agglutinated by the vesicles (human red blood cells) can be activated by incubation with gangliosides: insertion of the glycolipids in the plasma membranes makes them sensitive to the vesicle haemagglutinin.
Popoli
M
M
Laboratory of Neurochemistry, School of Medicine, Napoli, Italy.
Paterno
R
R
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005732:Gangliosides / Q000378:metabolism / Q000494:pharmacology; D006388:Hemagglutinins / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013572:Synaptic Vesicles / Q000378:metabolism*
D005732:Gangliosides; D006388:Hemagglutinins; D009419:Nerve Tissue Proteins; C016481:trisialoganglioside GT1