Synaptophysin binds to physophilin, a putative synaptic plasma membrane protein.
Synaptophysin binds to physophilin, a putative synaptic plasma membrane protein.
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DOI：
10.1083/jcb.111.5.2041
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发表时间：
1990-11
影响因子：
7.8
通讯作者：
Betz, H
中科院分区：
文献类型：
--
作者：
Thomas, L;Betz, H
我们开发了通过使用戊二醛固定或天然囊泡部分作为吸收基质来检测突触囊泡结合蛋白的程序。两种吸附剂都能在大鼠脑突触体和小鼠脑原代培养物中识别出 36 kD 的突出突触小泡结合蛋白。该蛋白与突触小泡的结合受到突触泡蛋白（突触泡的主要整合膜蛋白）的竞争，在 10(-8) 和 10(-7) M 突触泡蛋白之间出现半最大抑制。由于其对突触素的亲和力，我们将 36-kD 突触小泡结合蛋白命名为 physophilin（psi nu sigma alpha，希腊语 = 气泡、囊泡；psi iota lambda os，希腊语 = 朋友）。嗜酸蛋白的等电点约为 7.8，斯托克斯半径为 6.6 nm，表观沉降系数为 5.6 S，表明该蛋白质具有寡聚结构。它存在于由突触体制备的突触质膜中，但不存在于突触小泡中。在溶解实验中，嗜酸蛋白表现为完整的膜蛋白。因此，假定的突触质膜蛋白与突触小泡的主要膜蛋白之一表现出特异性相互作用。这种相互作用可能在突触小泡与突触前质膜的对接和/或融合中发挥作用。
We have developed procedures for detecting synaptic vesicle-binding proteins by using glutaraldehyde-fixed or native vesicle fractions as absorbent matrices. Both adsorbents identify a prominent synaptic vesicle-binding protein of 36 kD in rat brain synaptosomes and mouse brain primary cultures. The binding of this protein to synaptic vesicles is competed by synaptophysin, a major integral membrane protein of synaptic vesicles, with half-maximal inhibition seen between 10(-8) and 10(-7) M synaptophysin. Because of its affinity for synaptophysin, we named the 36-kD synaptic vesicle-binding protein physophilin (psi nu sigma alpha, greek = bubble, vesicle; psi iota lambda os, greek = friend). Physophilin exhibits an isoelectric point of approximately 7.8, a Stokes radius of 6.6 nm, and an apparent sedimentation coefficient of 5.6 S, pointing to an oligomeric structure of this protein. It is present in synaptic plasma membranes prepared from synaptosomes but not in synaptic vesicles. In solubilization experiments, physophilin behaves as an integral membrane protein. Thus, a putative synaptic plasma membrane protein exhibits a specific interaction with one of the major membrane proteins of synaptic vesicles. This interaction may play a role in docking and/or fusion of synaptic vesicles to the presynaptic plasma membrane.