Actin filaments in the acrosomal reaction of Limulus sperm. Motion generated by alterations in the packing of the filaments.
Actin filaments in the acrosomal reaction of Limulus sperm. Motion generated by alterations in the packing of the filaments.
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limulus精子的顶体反应中的肌动蛋白丝。通过细丝的包装改变产生的运动。
DOI：
10.1083/jcb.64.2.289
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发表时间：
1975-02
期刊：
影响因子：
--
通讯作者：
Tilney LG
中科院分区：
文献类型：
--
作者：
Tilney LG
当诱导鲎精子进行顶体反应时，在几秒钟内产生一个长度为50 μ m的过程。这个过程随着卵细胞的伸长而旋转，因此顶体过程实际上是螺旋穿过卵细胞的胶状物。在这个过程中是一束细丝，在诱导之前，这些细丝在精子内盘绕起来。精子中的丝束以三种稳定状态存在。其中一个状态可以在纯形式下被孤立。它仅由三种蛋白质组成，其分子量（mol wt）分别为43，000、55，000和95，000。基于其分子量、净电荷、形态、G-F转化和重的裂肌球蛋白（HMM）结合，43，000 mol wt蛋白是肌动蛋白。55，000 mol wt蛋白与肌动蛋白等摩尔比，不是微管蛋白，与肌动蛋白牢固结合，并抑制HMM结合。有证据表明，55，000 mol wt蛋白和95，000 mol wt蛋白（可能是α-辅肌动蛋白）也存在于鲎肌肉中。据推测，这些蛋白质在精子中的功能是将肌动蛋白丝保持在一起。在顶体反应之前，肌动蛋白丝相互缠绕成超螺旋;当反应完成时，肌动蛋白丝相互平行，形成肌动蛋白类晶体。它们包装的这种变化似乎引起顶体突起的运动，并受55，000 mol wt蛋白质和95，000 mol wt蛋白质的控制。
When Limulus sperm are induced to undergo the acrosomal reaction, a process, 50 mum in length, is generated in a few seconds. This process rotates as it elongates; thus the acrosomal process literally screws through the jelly of the egg. Within the process is a bundle of filaments which before induction are coiled up inside the sperm. The filament bundle exists in three stable states in the sperm. One of the states can be isolated in pure form. It is composed of only three proteins whose molecular weights (mol wt) are 43,000, 55,000, and 95,000. The 43,000 mol wt protein is actin, based on its molecular weight, net charge, morphology, G-F transformation, and heavy meromyosin (HMM) binding. The 55,000 mol wt protein is in equimolar ratio to actin and is not tubulin, binds tenaciously to actin, and inhibits HMM binding. Evidence is presented that both the 55,000 mol wt protein and the 95,000 mol wt protein (possibly alpha-actinin) are also present in Limulus muscle. Presumably these proteins function in the sperm in holding the actin filaments together. Before the acrosomal reaction, the actin filaments are twisted over one another in a supercoil; when the reaction is completed, the filaments lie parallel to each other and form an actin paracrystal. This change in their packing appears to give rise to the motion of the acrosomal process and is under the control of the 55,000 mol wt protein and the 95,000 mol wt protein.