Cysteine string protein (CSP) was discovered by use of a synapse-specific, monoclonal antibody to screen a cDNA expression library in Drosophila. A vertebrate CSP homolog was later identified and shown to co-purify with synaptic vesicles. CSP-α is now recognized as a membrane constituent of many regulated secretory organelles. Knockout of the csp gene in Drosophila produced temperature-sensitive paralysis reflecting a loss of evoked (but not spontaneous) transmitter release. However, CSP's role in regulated exocytosis remains ambiguous. Fruit flies lacking the csp gene also exhibited nerve terminal degeneration as did mice deficient in the csp-α gene. This phenotype has been ascribed to the depletion of a functional pool of the t-SNARE, SNAP-25. However, recent studies showing that an endosomal pool of CSP-α contributes to a novel, protein-export pathway argues that CSP's role in neurodegeneration is more complex. Clients of this later pathway include tau and α-synuclein, proteins linked to neurodegeneration. Additionally, mutations in the csp-α gene cause an adult-onset, neuronal ceroid lipofuscinosis and diminished CSP-α expression is an early event in Alzheimer's disease. Collectively, these findings indicate that much remains to be learned about the role of CSPs in cellular secretory pathways and human disease.

中文翻译：

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半胱氨酸串蛋白。

通过使用突触特异性单克隆抗体筛选果蝇中的cDNA表达文库，发现了半胱氨酸串蛋白（CSP）。后来确定了脊椎动物的CSP同源物，并显示与突触囊泡共纯化。现在，CSP-α被认为是许多受调节的分泌细胞器的膜成分。果蝇中csp基因的敲除导致温度敏感性麻痹，反映了诱发的（但不是自发的）递质释放的丧失。但是，CSP在调节性胞吐作用中的作用仍然不明确。缺乏csp基因的果蝇也表现出神经末梢变性，而csp-α基因缺陷的小鼠也是如此。该表型归因于t-SNARE SNAP-25的功能库的耗尽。但是，最近的研究表明，CSP-α的内体池有助于形成一种新颖的，蛋白质输出途径认为，CSP在神经退行性变中的作用更为复杂。后一条途径的客户包括tau和与神经变性相关的蛋白α-突触核蛋白。此外，csp-α基因的突变会导致成年发作，神经元类固醇脂褐藻病，而CSP-α表达减少是阿尔茨海默氏病的早期事件。总体而言，这些发现表明，关于CSP在细胞分泌途径和人类疾病中的作用还有很多事情要学习。