Basic studies on sperm-egg binding and applications to contraception

我们发现了一种新的精子蛋白sp38，它具有透明带（ZP）结合活性，位于许多哺乳动物物种的前部。它最初是从野猪附睾精子中纯化出来的38 kDa糖蛋白。根据纯化蛋白的部分氨基酸序列，从猪睾丸cDNA文库中分离到编码sp38的cDNA克隆。该cDNA编码一个含有350个氨基酸残基的前体蛋白，经翻译后修饰为含有299个氨基酸残基的成熟蛋白。Northern blot分析表明，sp38转录本仅在睾丸中表达。从猪的睾丸sDNA文库中分别获得了小鼠和人sp38的同源序列，显示出高度同源的序列。野猪sp38以钙依赖的方式与90kDa-ZP糖蛋白结合。sp38与ZP的结合特性与proacrosin相似。在体外卵精结合实验中，抗sp38抗体抑制精子与ZP的结合。

We founs a novel sperm protein sp38 with zona pellucida (ZP)-binding activity located at the anterior portion of many mammalian species. It was originally purified from boar epididymal sperm as a 38 kDa glycoprotein. The cDNA clones encoding sp38 was isolated from boar testis cDNA library based on the results of partial amino acid sequences of purified protein. The cDNA encoded a 350-residue amino acid precursor protein which was posttranslationally modified into a mature protein of 299 amino acid residues. Northern blot analysis demonstrated that the transcript of sp38 was expressed only in the testis. Mouse and human homologues of boar sp38 was obtained from testis sDNA libraries of respective species and showed highly homologous sequences. Boar sp38 bound to 90kDa-ZP glycoprotein species in a calcium-dependent manner. The binding characteristics of sp38 to the ZP were similar to those of proacrosin. Antibodies against sp38 inhibited the binding of sperm to the ZP in vitro egg-sperm binding assay.