title: Phospholipid methylation increases [3H]diazepam and [3H]GABA binding in membrane preparations of rat cerebellum.
abstract: The effect of phospholipid methylation on both [3H]diazepam and [3H]GABA ( [3H]gamma-aminobutyric acid) binding to crude synaptic plasma membrane from rat cerebellum has been studied. S-Adenosylmethionine (SAM) stimulates [3H]methyl group incorporation into membrane phospholipids and enhances [3H]diazepam binding by increasing the apparent Bmax. Conversely, inhibition of [3H]methyl group transfer from [3H]SAM to phospholipids by preincubation with SAM at 0 degrees C or with SAH abolishes the increase of binding. After preincubation with SAM, analysis of the GABA binding reveals the presence of binding sites with high affinity, a property absent in control membranes preincubated without SAM. Among the neurotransmitter bindings tested, only those of GABA and benzodiazepine in the cerebellum and beta-adrenergic ligands in the cerebral cortex are enhanced upon stimulation of phospholipid methyltransferase activity. [3H]Dihydromorphine, [3H]dihydro-alpha-ergokryptine and [3H]spiroperidol bindings are not affected by SAM. The present data suggest an involvement of phospholipid methylation in regulation of both [3H]GABA and [3H]-diazepam binding.
mesh_terms: D000818:Animals; D002531:Cerebellum / Q000378:metabolism*; D003975:Diazepam / Q000378:metabolism*; D007700:Kinetics; D008745:Methylation; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011963:Receptors, GABA-A; D012436:S-Adenosylmethionine / Q000378:metabolism*; D013570:Synaptic Membranes / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D010743:Phospholipids; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D012436:S-Adenosylmethionine; D003975:Diazepam