Lysosomal integral membrane protein LGP85 (LIMP-2) is ubiquitinated at the N-terminal cytoplasmic domain
Lysosomal integral membrane protein LGP85 (LIMP-2) is ubiquitinated at the N-terminal cytoplasmic domain
复制标题
溶酶体整合膜蛋白 LGP85 (LIMP-2) 在 N 端胞质结构域被泛素化
DOI：
10.1016/j.bbrc.2020.01.095
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发表时间：
2020
影响因子：
3.1
通讯作者：
Hirota Yuko
中科院分区：
文献类型：
--
作者：
Fujimoto Keiko;Uchida Shotaro;Amen Riham N.S.;Ishii Yuji;Tanaka Yoshitaka;Hirota Yuko
LGP 85/LIMP-2是溶酶体的一种III型跨膜糖蛋白，其N-末端未切割的信号序列和C-末端疏水结构域穿过膜两次。除了作为溶酶体酶β-葡萄糖脑苷脂酶和几种肠道病毒的受体外，LGP 85在内体/溶酶体区室（ELC）的生物发生和维持中发挥关键作用。我们以前的研究已经证明，大鼠LGP 85过表达到COS细胞中导致ELC扩大，膜运输受损。我们在这里表明，大鼠LGP 85是聚泛素化的N-末端短胞质结构域，仅包括三个氨基酸残基，丙氨酸，精氨酸和半胱氨酸。在N-末端胞质结构域中用丙氨酸取代精氨酸或半胱氨酸不影响LGP 85的泛素化，从而表明泛素（Ub）与N-末端丙氨酸残基的α-NH 2基团缀合。此外，我们能够定义一个结构域必需的泛素化的区域范围内的氨基酸156至255的内腔结构域的LGP 85。这是第一个报告显示，整体溶酶体膜蛋白LGP 85是泛素化。
LGP85/LIMP-2 is a type III transmembrane glycoprotein of lysosomes, which traverses the membrane twice with an N-terminal uncleaved signal sequence and C-terminal hydrophobic domain. In addition to functioning as a receptor for a lysosomal enzyme β-glucocerebrosidase and for several enteroviruses, LGP85 plays a key role in the biogenesis and maintenance of endosomal/lysosomal compartments (ELCs). Our previous studies have demonstrated that overexpression of rat LGP85 into COS cells results in the enlarged ELCs, from where membrane trafficking is impaired. We show here that rat LGP85 is polyubiquitinated at the N-terminal short cytoplasmic domain that comprises of only three amino acid residues, alanine, arginine, and cysteine. Replacement of either arginine or cysteine with alanine within the N-terminal cytoplasmic domain did not influence the ubiquitination of LGP85, thereby indicating that ubiquitin (Ub) is conjugated to the α-NH2group of the N-terminal alanine residue. Furthermore, we were able to define a domain necessary for ubiquitination in a region ranging from the amino acids 156 to 255 within the lumenal domain of LGP85. This is the first report showing that the integral lysosomal membrane protein LGP85 is ubiquitinated.