Bilak M, Askanas V, Engel W K
Department of Neurology, University of Southern California School of Medicine, Los Angeles 90017.
Synapse. 1994 Apr;16(4):280-3. doi: 10.1002/syn.890160405.
alpha 1-Antichymotrypsin (alpha 1-ACT) is an early-stage acute-phase plasma protein and a serpin that preferentially inactivates chymotrypsin, cathepsin G, and chymase. Using immunofluorescence with four rabbit polyclonal and two monoclonal specific antibodies against human alpha 1-ACT, we have localized alpha 1-ACT at human and rat neuromuscular junctions (NMJs). Strong alpha 1-ACT immunoreactivity (IR) was present at all NMJs identified by bound alpha-bungarotoxin (alpha-BT). alpha 1-ACT immunoreactivity typically extended slightly deeper into the muscle fiber than alpha-BT, and it closely co-localized with immunoreactivities of post-synaptic desmin, beta-amyloid precursor protein, and dystrophin at the same double- or triple-labeled NMJs. Topography of alpha 1-ACT-IR was the same at human and rat NMJs. The muscle non-junctional sarcolemma was either not immunoreactive or was only very slightly so. When the primary antibody was omitted, absorbed, or replaced by a non-immune serum, there was no immunostaining. Thus, alpha 1-ACT is a novel component of the NMJ. Although its role in the postsynaptic domain of the NMJ is unknown, it might be involved in the interaction between the presynaptic and postsynaptic components and/or inhibit excessive or unwanted serine proteases that may exist in the region of the NMJ.
α1抗糜蛋白酶（α1-ACT）是一种早期急性期血浆蛋白，属于丝氨酸蛋白酶抑制剂家族，它能优先使糜蛋白酶、组织蛋白酶G和糜酶失活。我们运用免疫荧光技术，使用四种兔多克隆抗体和两种针对人α1-ACT的单克隆特异性抗体，将α1-ACT定位到人和大鼠的神经肌肉接头（NMJ）处。在所有由结合的α-银环蛇毒素（α-BT）鉴定出的NMJ处均存在强烈的α1-ACT免疫反应性（IR）。α1-ACT免疫反应性通常比α-BT稍深入肌肉纤维一些，并且在相同的双标或三标NMJ处，它与突触后结蛋白、β淀粉样前体蛋白和肌营养不良蛋白的免疫反应性紧密共定位。人和大鼠NMJ处α1-ACT-IR的拓扑结构相同。肌肉非连接性肌膜要么没有免疫反应性，要么只有非常轻微的免疫反应性。当省略一抗、用吸收法处理一抗或用非免疫血清替代一抗时，均无免疫染色现象。因此，α1-ACT是NMJ的一种新成分。尽管其在NMJ突触后区域的作用尚不清楚，但它可能参与突触前和突触后成分之间的相互作用，和/或抑制NMJ区域可能存在的过量或不必要的丝氨酸蛋白酶。
