Soluble and membrane-bound S-100 protein in cerebral cortex synaptosomes. Properties of the S-100 receptor.
Within cerebral cortex synaptosomes, S-100 protein can be recovered in two forms: soluble and membrane-bound. Synaptosomal S-100 is mainly a soluble protein (85 percent). The membrane-bound S-100 is differently distributed in the synaptosomal membranes, intraterminal mitochondria, and synaptic vesicles. S-100 binds to a specific receptor. The binding is time-dependent, reversible and saturable with respect to S-100. The number of receptors is calculated to be about 9 times 10(12)/mg protein, since saturation is achieved at 31 ng [125I]S-100/0.1 mg protein of disrupted synaptosomes. The rate constant for association of S-100 with its receptor at 37 degrees C, k1, is 4.74 times 10(4) M(-1) sec(-1), and the rate constant for dissociation, k-1, 9.24 times 10(-4) sec(-1).
D000818:Animals; D001665:Binding Sites; D002540:Cerebral Cortex / Q000032:analysis* / Q000378:metabolism / Q000648:ultrastructure; D006168:Guinea Pigs; D009419:Nerve Tissue Proteins / Q000032:analysis*; D009418:S100 Proteins / Q000032:analysis* / Q000378:metabolism; D013574:Synaptosomes / Q000032:analysis* / Q000378:metabolism
D009419:Nerve Tissue Proteins; D009418:S100 Proteins