Signal molecules in the jelly coat of starfish eggs for the inducing of acrosome reaction.

顶体反应（AR）是精子对卵细胞的一种特异性胞吐反应。在海星Asterias amurensis中，卵的胶状外套中的三种组分协同作用于精子以引起AR ;即顶体反应诱导物质（阿里斯）、Co-ARIS和名为astersaps的精子激活肽。阿里斯是一种表观分子大小超过10 ^7的高度硫酸化糖蛋白，其活性主要归因于硫酸化糖链。阿里斯的主要糖链是一个非常长的（分子大小为2 × 106以上）五糖重复单元的线性聚合物（Fr.1），能够在高钙浓度下诱导AR，与阿里斯一样。为了获得阿里斯受体的结合参数，使用放射性标记的Fr. 1通过离心结合测定进行结合实验。将精子与放射性碘标记的Fr.1孵育。Scatchard图显示，受体有两种类型，高亲和力型（Kd ; 145 μ M，Bmax ; 8.38 × 10 ~ 4）和低亲和力型（Kd ; 4.43 × 10 ~ 2 μ M，Bmax; 1.89 × 10 ~ 6）。用未标记的Fr.1和标记的Fr.1进行竞争性测定<125>。测量配体的结合和游离浓度。结果表明，未标记的Fr.1抑制与标记的Fr.1结合。

The acrosome reaction (AR) is a species-specific exocytosis response of spermatozoa to the egg envelopment. In the starfish Asterias amurensis, three components in the jelly coat of eggs act in concert on spermatozoa to elicit the AR ; namely acrosome reaction-inducing substance (ARIS), Co-ARISs and sperm-activating peptides named asterosaps. ARIS is highly sulfated glycoprotein of an apparent molecular size over 10^7 and its activity is mostly attributable to sulfated sugar chains. The main saccharide chain of ARIS is a very long (2 x 10^6 in more in molecular size) linear polymer of the pentasaccharide repeating units (Fr.1) is able to induce the AR at high calcium concentration as well as ARIS does. To obtain binding parameters of an ARIS receptor, binding experiments were carried out by centrifugation binding assay using radio-labeled Fr.1. Spermatozoa were incubated with radioactive iodinated Fr.1. With Scatchard plot, there are two type receptor, High affinity type (Kd ; 145 muM,Bmax ; 8.38 x 10^4) and low affinity type (Kd ; 4.43 x 10^2muM,Bmax ; 1.89 x 10^6). And competitive assay were carried with non-labeled Fr.1 and ^<125>I labeled Fr.1. The bound and free concentration of the ligand were measured. The result showed that non-labeled Fr.1 inhibits to bind labeled Fr.1.