Secretory phospholipase A₂ (sPLA₂) plays important roles in phospholipid metabolism, skin barrier maintenance, immune response and other processes in organisms. sPLA₂ of sea cucumber A. japonicus (AjPLA₂) has not yet been reported. This study successfully amplified the AjPLA₂ sequence. The total cDNA of AjPLA₂ is 931 bp, including a 480 bp ORF that encodes 159 amino acids. The AjPLA₂ protein includes a 16-aa signal peptide, a 5-aa precursor peptide and a 138-aa mature peptide. Homologous alignment showed that AjPLA₂ and the sPLA₂s from starfish have the typical domains of the Group IB sPLA₂. And additional amino acid sequences were found around the β-Wing, which is different from the Group IB sPLA₂. These results showed that AjPLA₂ and sPLA₂s from starfish all belong to a new group in the Group I sPLA₂ family. AjPLA₂ is widely distributed in sea cucumber tissues. The functional analysis also showed that AjPLA₂ was upregulated in the intestine by feeding. When the body wall was damaged, it was significantly upregulated around the wound. And the expression levels of AjPLA₂ were significantly increased in V. splendens-infected sea cucumbers. The results indicated that AjPLA₂ plays roles in the sea cucumber immunologic process. Combined with the upregulation of unsaturated fatty acids (PUFAs) content in A. japonicus, it demonstrated that AjPLA₂ could participate in the immune of A. japonicus by hydrolyzing phospholipid and releasing PUFAs. This study had a solid foundation for the further research of AjPLA₂ gene function in vivo, development and application of AjPLA₂ protein.

分泌型磷脂酶A ₂ (sPLA ₂ )在生物体的磷脂代谢、皮肤屏障维护、免疫反应等过程中发挥着重要作用。海参sPLA ₂ (AjPLA 2 ₎尚未见报道。本研究成功扩增了AjPLA ₂序列。_{AjPLA 2}的cDNA总长为931 bp，包括编码159个氨基酸的480 bp ORF。AjPLA ₂蛋白包括16个氨基酸的信号肽、5个氨基酸的前体肽和138个氨基酸的成熟肽。同源比对表明AjPLA ₂和海星的sPLA ₂具有IB组sPLA ₂的典型结构域。并且在β-Wing周围发现了额外的氨基酸序列，这与IB组sPLA ₂不同。这些结果表明，来自海星的 AjPLA ₂和 sPLA ₂均属于 I 组 sPLA ₂家族中的一个新组。AjPLA ₂广泛分布于海参组织中。功能分析还表明，AjPLA ₂在肠道中通过进食而上调。当体壁受损时，伤口周围的表达显着上调。感染芨芨草的海参中AjPLA ₂的表达水平显着升高。结果表明AjPLA ₂在海参免疫过程中发挥作用。结合刺参中不饱和脂肪酸(PUFA)含量的上调，证明AjPLA _{2可以通过水解磷脂并释放PUFA来参与}刺参的免疫。本研究为进一步研究AjPLA ₂基因的体内功能、AjPLA ₂蛋白的开发和应用奠定了坚实的基础。