Department of Cell Biology, Yale University School of Medicine, New Haven, CT.
Max Planck Institute of Biochemistry, Department of Molecular Medicine, Martinsried, Germany.
J Cell Biol. 2020 Jun 1;219(6). doi: 10.1083/jcb.201910089.
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.
TGN 是新合成蛋白质分拣和分泌的关键隔室。在 TGN 处，可溶性蛋白质根据其寡糖侧链所携带的指令或涉及货物分拣蛋白 Cab45 的 Ca2+介导过程进行分拣。在这里，我们表明 Cab45 被高尔基特异性蛋白激酶 Fam20C 磷酸化。磷酸化模拟将 Cab45 易位到 TGN 衍生的囊泡中，这伴随着 Cab45 客户 LyzC 的出口增加。我们的发现表明 Fam20C 通过精细调节 Cab45 寡聚化在 Cab45 客户的输出中发挥关键作用，从而影响 TGN 中 Cab45 的保留。
