Developmental changes in protein carboxylmethylation and in the benzodiazepine receptor proteins in rat brain.

The intraventricular administration of [3H-methyl]-methionine resulted in a steady increase in carboxyl-[3H]methylated protein formation in the brain of developing rats (2-42 days). The analysis by gel filtration on Sepharose-4B of Lubrol-Px-solubilized membrane proteins, including benzodiazepine receptor proteins, revealed co-migration of carboxyl-[3H]methylated and [3H]flunitrazepam-binding protein species. The latter displayed a single peak at 2 days and 2-3 peaks subsequently. At 26 days the lighter of the two [3H]flunitrazepam and [3H]muscimol-binding peaks associated with the principal carboxyl-[3H]-methylated protein peak. The findings suggest the participation of carboxyl-methylation in the maturation of benzodiazepine receptor proteins.