Neuroserpin is a serine protease inhibitor expressed mainly in the brain and at low levels in other tissues like the kidney, testis, heart, and spinal cord. It is involved in the inhibition of tissue plasminogen activator (tPA), plasmin, and to a lesser extent, urokinase-type plasminogen (uPA). Neuroserpin has also been shown to plays noninhibitory roles in the regulation of N-cadherin-mediated cell adhesion. It is involved in neuroprotection from seizure and stroke through tPA-mediated inhibition and also through its other protease targets. Mutations in critical domains of neuroserpin lead to its polymerization and neuronal death. In this study, a novel truncated isoform of human neuroserpin was identified in the brain and liver, which was confirmed by reverse transcriptase-PCR and DNA sequencing using exon-specific primers. Structural characterization of novel isoform using MD simulations studies indicated that it lacks the reactive center loop (RCL) but largely maintains its secondary structure fold. The novel truncated variant was cloned, expressed, and purified. A comparative intrinsic fluorescence and 4,4′-bis-1-anilino naphthalene 8-sulfonate studies revealed a decrease in fluorescence emission intensity and a more exposed hydrophobic surface as compared to the reported isoform. However, the novel isoform has lost its ability for tPA inhibition and complex formation. The absence of RCL indicates a noninhibitory role for the truncated isoform, prompting a detailed search and identification of two smaller isoforms in the human brain. With indications of the noninhibitory role of neuroserpin, identifying novel isoforms that appear to be without the tPA recognition domain is significant.

中文翻译：

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检测缺乏反应中心环的截短的人神经丝氨酸亚型：非抑制作用的意义

Neuroserpin 是一种丝氨酸蛋白酶抑制剂，主要在大脑中表达，在肾脏、睾丸、心脏和脊髓等其他组织中含量较低。它参与抑制组织纤溶酶原激活物 (tPA)、纤溶酶，并在较小程度上抑制尿激酶型纤溶酶原 (uPA)。Neuroserpin 还被证明在调节 N-钙粘蛋白介导的细胞粘附中发挥非抑制性作用。它通过 tPA 介导的抑制以及通过其其他蛋白酶靶点参与对癫痫发作和中风的神经保护。神经丝氨酸关键领域的突变导致其聚合和神经元死亡。在这项研究中，在大脑和肝脏中鉴定了一种新型截短的人类神经丝氨酸同工型，通过逆转录酶-PCR 和使用外显子特异性引物的 DNA 测序证实了这一点。使用 MD 模拟研究对新型异构体的结构表征表明，它缺乏反应中心环 (RCL)，但在很大程度上保持其二级结构折叠。新的截短变体被克隆、表达和纯化。比较固有荧光和 4,4'-bis-1-anilino naphthalene 8-sulfonate 研究表明，与报告的同工型相比，荧光发射强度降低，疏水表面更暴露。然而，新的异构体已经失去了抑制 tPA 和形成复合物的能力。RCL 的缺失表明截断同种型的非抑制作用，促使对人脑中两种较小的同种型进行详细搜索和鉴定。随着神经丝氨酸非抑制作用的迹象，