The TGN is a key compartment for the sorting and secretion of newly synthesized proteins. At the TGN, soluble proteins are sorted based on the instructions carried in their oligosaccharide backbones or by a Ca2+-mediated process that involves the cargo-sorting protein Cab45. Here, we show that Cab45 is phosphorylated by the Golgi-specific protein kinase Fam20C. Mimicking of phosphorylation translocates Cab45 into TGN-derived vesicles, which goes along with an increased export of LyzC, a Cab45 client. Our findings demonstrate that Fam20C plays a key role in the export of Cab45 clients by fine-tuning Cab45 oligomerization and thus impacts Cab45 retention in the TGN.

中文翻译：

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Fam20C 通过 Cab45 磷酸化调节蛋白质分泌

TGN 是新合成蛋白质分选和分泌的关键区室。在 TGN，可溶性蛋白质根据寡糖主链中携带的指令或通过涉及货物分选蛋白 Cab45 的 Ca2+ 介导过程进行分选。在这里，我们证明 Cab45 被高尔基体特异性蛋白激酶 Fam20C 磷酸化。模仿磷酸化将 Cab45 易位到 TGN 衍生的囊泡中，这伴随着 Cab45 客户 LyzC 的输出增加。我们的研究结果表明，Fam20C 通过微调 Cab45 寡聚化，在 Cab45 客户的导出中发挥着关键作用，从而影响 Cab45 在 TGN 中的保留。