Chang L R, Barnard E A
J Neurochem. 1982 Dec;39(6):1507-18. doi: 10.1111/j.1471-4159.1982.tb07983.x.
The molecular size of the benzodiazepine (BZ) receptor in the synaptic membrane of brain cortex (bovine or rat) was determined by an improved version of the radiation inactivation method to be 220,000. An identical size was found simultaneously for the associated gamma-aminobutyric acid (GABA) receptor and for the component binding beta-carboline esters. It is proposed that all three activities reside in a single protein or protein complex in the membrane. The size in solution, after extraction into Triton X-100 medium from exhaustively washed membranes, was estimated by sedimentation constant (9.4S) and by gel filtration ( approximately 230,000 apparent MW), again with the BZ and GABA binding activities behaving identically. This size applies to the component that undergoes photoaffinity labelling by [3H]flunitrazepam in the membrane, and contains a 51,000 Mr polypeptide as the BZ-binding subunit. It is concluded that a protein complex or oligomer of 200,000-220,000 MW carries a class of BZ-binding sites and an associated class of GABAA sites.
采用辐射失活法的改进版本测定了大脑皮层（牛或大鼠）突触膜中苯二氮䓬（BZ）受体的分子大小为220,000。同时发现相关的γ-氨基丁酸（GABA）受体和结合β-咔啉酯的成分具有相同的大小。有人提出，这三种活性都存在于膜中的单一蛋白质或蛋白质复合物中。从彻底洗涤过的膜中提取到Triton X-100培养基后，通过沉降常数（9.4S）和凝胶过滤（表观分子量约为230,000）估计溶液中的大小，BZ和GABA结合活性的表现再次相同。这个大小适用于膜中经[3H]氟硝西泮进行光亲和标记的成分，并且含有一个51,000 Mr的多肽作为BZ结合亚基。结论是，一个分子量为200,000 - 220,000的蛋白质复合物或寡聚物携带一类BZ结合位点和一类相关的GABAA位点。
