牛小脑γ-氨基丁酸受体的生化特性

用放射性配基结合实验方法鉴定了牛小脑γ-氨基丁酸(GABA)受体的生化特性。高速离心制备的牛小脑突触膜与~3H-GABA有一饱和结合,K_D值为96nM,B_(max)为1.02pmol/mg蛋白,Hill系数为0.99。这一结合具有药理专一性和立体专一性,动力学实验测得结合速度常数为9.6×10~6M~(-1)min~(-1),解离速度常数为0.115min~(-1)。冻融、洗涤、超声波和TritonX-100处理突触膜,使~3H-GABA结合活性增加114倍。

BIOCHEMICAL CHARACTERISTICS OF GABA RECEPTOR ON CRUDE SYNAPTIC MEMBRANE FROM OX CEREBULLUM

This paper reports the radioactive ligand binding technique for GABA receptor and the biochemical char acteristics of GABA receptor of ox cerebellum.The crude synaptic membrane fraction of ox cerebullum was prepared by high speed centrifugation. 3H-GABA binding to receptor on synaptic membrane is a saturate process, and with a dissociation constant of 96 nM, maximum number of binding site of 1.02 Pmol/mg protein and Hill number of 0.99. In binding with GABA receptor, compounds differ from each other in their pharmacological and stereo-scopic specificities. The kinetic constants of GABA receptor binding activity were determined by observed rate method. The rate con-stants for association and dissociation were 9.6×106 M-1 min-1 aud 0.115 min-1 respectively. The activty was increased to 114 fold by supersonic, freezing, thawing, washing and Triton X-100 treatment.