Background: Prmt5 plays major role in regulation of gene expression, RNA processing, cell growth and differentiation, signal transduction, germ cell development, etc., in mammals. Prmt5 is also related to cancer. Knowing the proteins interacting with Prmt5 is important to understand Prmt5’s function in cells. Although there have been reports on proteins binding with Prmt5 in mammals, the partner proteins of Prmt5 in fish are still unclear.

Objectives: The objective was to obtain proteins that bind with Prmt5 in medaka, a model fish.

Methods: Yeast two hybridization was adopted to achieve the objective. Medaka Prmt5 was used as a bait to fish the prey, binding proteins in a cDNA library of medaka. Co-immunoprecipitation and in silicon analysis were performed to study the interaction of medaka Mep50 and Prmt5.

Results: Eight proteins were identified to bind with Prmt5 from 69 preliminary positive colonies. The binding proteins are methylosome protein 50 (Mep50), apolipoprotein A-I-like (Apo-AI), PR domain containing protein 1a with zinc fingers (Prdm1a), Prdm1b, T-cell immunoglobulin mucin family member 3 (Tim-3), phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthase (Paics), NADH dehydrogenase subunit 4 (ND4) and sciellin (Scl). Co-immunoprecipitation confirmed the interaction of medaka Prmt5 and Mep50. Predicted structures of medaka Prtm5 and Mep50 are similar to that of human PRMT5 and MEP50.

Conclusion: Medaka Mep50, Prdm1a, Prdm1b, Apo-AI, Tim-3, Paics, ND4, and Scl bind with Prmt5.

背景：Prmt5在调节哺乳动物的基因表达，RNA加工，细胞生长和分化，信号转导，生殖细胞发育等方面起着重要作用。Prmt5也与癌症有关。了解蛋白质与Prmt5的相互作用对于理解Prmt5在细胞中的功能很重要。尽管已有关于哺乳动物中与Prmt5结合的蛋白质的报道，但鱼中Prmt5的伴侣蛋白质仍不清楚。

目的：目的是在模型鱼medaka中获得与Prmt5结合的蛋白质。

方法：采用酵母二杂交技术达到目的。Medaka Prmt5用作诱饵来捕捞猎物，结合蛋白在medaka cDNA文库中。进行了免疫共沉淀和硅分析，以研究medaka Mep50和Prmt5的相互作用。

结果：从69个初步阳性菌落中鉴定出8种蛋白质与Prmt5结合。结合蛋白是甲基脂质体蛋白50（Mep50），类似载脂蛋白AI的蛋白（Apo-AI），带有锌指的蛋白PR结构域1a（Prdm1a），Prdm1b，T细胞免疫球蛋白粘蛋白家族成员3（Tim-3），磷酸核糖氨基咪唑羧化酶和磷酸核糖氨基咪唑琥珀酰羧酰胺合酶（Paics），NADH脱氢酶亚基4（ND4）和sciellin（Scl）。免疫共沉淀证实了medaka Prmt5和Mep50的相互作用。medaka Prtm5和Mep50的预测结构与人PRMT5和MEP50的结构相似。

结论：Medaka Mep50，Prdm1a，Prdm1b，Apo-AI，Tim-3，Paics，ND4和Scl与Prmt5结合。