中文摘要：

首次在瘤背石磺（Onchidium struma）中克隆得到一种新的表皮生长因子（EGF）的cDNA序列全长。EGF基因cDNA的全长为1158bp, 命名为Os-egf1,其中开放阅读框长度为846 bp,编码一条包含281个氨基酸残基的多肽链。根据氨基酸序列比对和结构域分析结果发现其含有2个保守的EGF结构域和1个EGF-like结构域, 每个结构域中均包含至少6个半胱氨酸残基, 且形成CX7 CX4-5 CX10-13 CXCX8 C结构, 其结构域由C1～C3、C2～C4和C5～C6之间形成的3个二硫键维持, 符合表皮生长因子家族及其相关蛋白的特征结构域, 但其余氨基酸序列与现有相关基因差异较大, 推测可能是一种新的EGF-like基因。利用MEGA6.0软件构建Os-egf与EGF家族相关蛋白的系统进化树, 表明EGF家族蛋白具有一定的物种特异性。

英文摘要：

The complete cDNA sequence of the EGF-like gene was cloned from Onchidium struma for the first time. cDNA of the EGF-like gene was named Os-egf1; it consisted of 1158 bp containing a 846-bp ORF that encoded a peptide of 281 amino acids. Multiple alignment and conserved domain analysis indicated that this peptide chain contained two conserved EGF domains and one EGF-like domain. Each domain contained at least six cysteine residues （CX7 CX4–5 CX10–13 CXCX8 C） that can form three disulfide bonds between C1 and C3, C2 and C4, and C5 and C6. These characteristics are consistent with the EGF protein family. However, the remaining sequences of Os-egf1 were considerably different from other members of the EGF family. Thus, we proposed that Os-egf1 is a novel EGF-like gene. A phylogenetic tree was built using MEGA6.0 to investigate the relationship between Os-egf1 and proteins belonging to the EGF family. The study also suggested that proteins belonging to the EGF family are species-specific.