Apperson M L, Moon I S, Kennedy M B
Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
J Neurosci. 1996 Nov 1;16(21):6839-52. doi: 10.1523/JNEUROSCI.16-21-06839.1996.
We purified an abundant protein of apparent molecular mass 180 kDa from the postsynaptic density fraction of rat forebrain and obtained amino acid sequences of three tryptic peptides generated from the protein. The sequences were used to design a strategy for cloning the cDNA encoding the protein by polymerase chain reaction. The open reading frame of the cDNA encodes a novel protein of predicted molecular mass 167 kDa. We have named the protein densin-180. Antibodies raised against the predicted amino and carboxyl sequences of densin-180 recognize a 180 kDa band on immunoblots that is enriched in the postsynaptic density fraction. Immunocytochemical localization of densin-180 in dissociated hippocampal neuronal cultures shows that the protein is highly concentrated at synapses along dendrites. The message encoding densin-180 is brain specific and is more abundant in forebrain than in cerebellum. The sequence of densin-180 contains 17 leucine-rich repeats, a sialomucin domain, an apparent transmembrane domain, and a PDZ domain. This arrangement of domains is similar to that of several adhesion molecules, in particular GPIbalpha, which mediates binding of platelets to von Willebrand factor. We propose that densin-180 participates in specific adhesion between presynaptic and postsynaptic membranes at glutamatergic synapses.
我们从大鼠前脑的突触后致密部分中纯化出一种表观分子量为180 kDa的丰富蛋白质，并获得了该蛋白质产生的三个胰蛋白酶肽段的氨基酸序列。这些序列被用于设计一种通过聚合酶链反应克隆编码该蛋白质的cDNA的策略。该cDNA的开放阅读框编码一种预测分子量为167 kDa的新蛋白质。我们将该蛋白质命名为致密素-180。针对致密素-180预测的氨基和羧基序列产生的抗体在免疫印迹中识别出一条180 kDa的条带，该条带在突触后致密部分中富集。致密素-180在解离的海马神经元培养物中的免疫细胞化学定位表明，该蛋白质高度集中在沿树突的突触处。编码致密素-180的信息是脑特异性的，在前脑中比在小脑中更丰富。致密素-180的序列包含17个富含亮氨酸的重复序列、一个唾液粘蛋白结构域、一个明显的跨膜结构域和一个PDZ结构域。这种结构域的排列类似于几种粘附分子，特别是GPIα，它介导血小板与血管性血友病因子的结合。我们提出致密素-180参与谷氨酸能突触处突触前膜和突触后膜之间的特异性粘附。
