Stabilization of hepatic colchicine-binding activity by organic acids.
Previous work has shown that the total hepatic tubulin pool and the hepatic microtubule-derived tubulin pool do not have identical [3H]colchicine binding properties. Rapid loss of colchicine-binding activity was noted in the microtubule-derived fractions of liver tubulin. Furthermore, quantitative determination of the total and polymerized tubulin in the liver by the [3H]colchicine-binding assay was hampered by rapid and unequal loss of binding sites under assay conditions. The organic acids, glutamate and glucose 1-phosphate, have been shown to stabilize calf brain tubulin against loss of colchicine-binding sites. Therefore, these compounds were tested as possible protecting agents against loss of colchicine binding activity of liver tubulin. It was found that these agents stabilized liver tubulin under [3H]colchicine-binding conditions. Additional experiments showed that these agents also prevented the rapid loss of colchicine-binding activity that occurred when purified brain tubulin was exposed to liver supernates. These results suggest that the inclusion of the organic acids, glutamate and glucose 1-phosphate, may modify the time decay properties of liver tubulin in solution. Further, these data suggest that these protecting agents may be of analytical value in [3H]colchicine-binding assay systems for liver tubulin.
D000818:Animals; D002264:Carboxylic Acids / Q000494:pharmacology*; D003078:Colchicine / Q000378:metabolism*; D005958:Glucosephosphates / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains; D012970:Sodium Glutamate / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism*
D002264:Carboxylic Acids; D005958:Glucosephosphates; D014404:Tubulin; C031590:glucose-1-phosphate; D003078:Colchicine; D012970:Sodium Glutamate