Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, Japan.
J Biochem. 2010 Oct;148(4):439-48. doi: 10.1093/jb/mvq086. Epub 2010 Aug 2.
Hatching of medaka embryos from the fertilized egg envelope involves two enzymes, HCE and LCE. HCE swells the envelope and then LCE completely dissolves it. We determined HCE and LCE cleavage sites on the egg envelope that are primarily constructed of two groups of subunit proteins, ZI-1,2 and ZI-3. HCE and LCE cleaved different target sequences on the egg envelope proteins but shared one common cleavage site. HCE cleaved the N-terminal region of ZI-1,2 and ZI-3, mainly the Pro-Xaa-Yaa repeat sequence of ZI-1,2 into hexapeptides, but not the site within a zona pellucida (ZP) domain that is considered to be the core structure of the egg envelope. The cleavage of these N-terminal regions results in swelling and softening of the envelope. LCE cleaved the middle of the ZP domain of ZI-1,2, in addition to the upstream of the trefoil domain of ZI-1,2 and the ZP domain of ZI-3. This middle site is in the intervening sequence connecting two subdomains of the ZP domain. Cleaving this site would result in the solubilization of the swollen egg envelope by the disruption of the filamentous structure that is thought to be formed by the non-covalent polymerization of ZP domains.
从受精卵囊孵化出的泥鳅胚胎涉及两种酶，HCE 和 LCE。HCE 使囊膨胀，然后 LCE 完全溶解它。我们确定了卵囊的 HCE 和 LCE 裂解位点，卵囊主要由两组亚基蛋白 ZI-1、2 和 ZI-3 构成。HCE 和 LCE 在卵囊蛋白上切割不同的靶序列，但有一个共同的切割位点。HCE 切割 ZI-1、2 和 ZI-3 的 N 端区域，主要是 ZI-1、2 的 Pro-Xaa-Yaa 重复序列成六肽，但不切割被认为是卵囊核心结构的透明带 (ZP) 结构域内的位点。这些 N 端区域的切割导致囊的膨胀和软化。LCE 切割 ZI-1、2 的 ZP 结构域的中部，以及 ZI-1、2 的三叶结构域的上游和 ZI-3 的 ZP 结构域。该中间位点位于 ZP 结构域的两个亚结构域之间的间隔序列中。切割该位点会破坏被认为是由 ZP 结构域的非共价聚合形成的丝状结构，从而导致膨胀的卵囊溶解。
