Pomin Vitor H
Program of Glycobiology, Institute of Medical Biochemistry Leopoldo de Meis, and University Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, 21941-913, Brazil,
Glycoconj J. 2015 Feb;32(1-2):9-15. doi: 10.1007/s10719-015-9573-y. Epub 2015 Jan 31.
Fertilization is a controlled cell-cell interaction event that ultimately leads to the union of the gametes involved in reproduction. Fertilization is characterized by three major steps: (i) sperm binding to the extracellular matrix that coats the egg, inducing thereby the acrosome reaction; (ii) penetration of the acrosome-reacted sperm through the egg coat until its contact with the egg plasma membrane; and (iii) adhesion and fusion of the cell membranes of both gametes and the interchange of genetic materials. The acrosome reaction in the first step is important because it ensures that fertilization occurs only between gametes of homologous species. This specificity is primarily driven by the structure of egg jelly coat glycans recognized by a lectin-like binding protein (receptor) in the sperm membrane. Sea urchin fertilization is the best model utilized for understanding carbohydrate-mediated acrosome reactions. This report aims at describing the biochemical basis of regulatory mechanisms exerted by sea urchin sulfated fucans and galactans of well-defined chemical structures on the egg-sperm recognition process during fertilization of this invertebrate. Flagellasialin, a sulfated polysialic acid-containing glycoprotein found in sea urchin sperm flagella, is another sulfated glycan example also involved in fertilization of the echinoderm.
受精是一个受调控的细胞间相互作用事件，最终导致参与生殖的配子结合。受精具有三个主要步骤：（i）精子与包裹卵子的细胞外基质结合，从而诱导顶体反应；（ii）顶体反应后的精子穿透卵膜直至与卵质膜接触；（iii）两个配子的细胞膜黏附与融合以及遗传物质的交换。第一步中的顶体反应很重要，因为它确保受精仅发生在同源物种的配子之间。这种特异性主要由精子膜中一种凝集素样结合蛋白（受体）识别的卵黄膜聚糖结构驱动。海胆受精是用于理解碳水化合物介导的顶体反应的最佳模型。本报告旨在描述具有明确化学结构的海胆硫酸化岩藻聚糖和半乳聚糖在这种无脊椎动物受精过程中对精卵识别过程施加调控机制的生化基础。鞭毛唾液酸蛋白是一种存在于海胆精子鞭毛中的含硫酸化多唾液酸的糖蛋白，也是另一个参与棘皮动物受精的硫酸化聚糖实例。
