Santos António J M, Nogueira Cristina, Ortega-Bellido Maria, Malhotra Vivek
Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08002 Barcelona, Spain.
Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08002 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
J Cell Biol. 2016 May 9;213(3):343-54. doi: 10.1083/jcb.201603072. Epub 2016 May 2.
Procollagens, pre-chylomicrons, and pre-very low-density lipoproteins (pre-VLDLs) are too big to fit into conventional COPII-coated vesicles, so how are these bulky cargoes exported from the endoplasmic reticulum (ER)? We have shown that TANGO1 located at the ER exit site is necessary for procollagen export. We report a role for TANGO1 and TANGO1-like (TALI), a chimeric protein resulting from fusion of MIA2 and cTAGE5 gene products, in the export of pre-chylomicrons and pre-VLDLs from the ER. TANGO1 binds TALI, and both interact with apolipoprotein B (ApoB) and are necessary for the recruitment of ApoB-containing lipid particles to ER exit sites for their subsequent export. Although export of ApoB requires the function of both TANGO1 and TALI, the export of procollagen XII by the same cells requires only TANGO1. These findings reveal a general role for TANGO1 in the export of bulky cargoes from the ER and identify a specific requirement for TALI in assisting TANGO1 to export bulky lipid particles.
前胶原蛋白、前乳糜微粒和前极低密度脂蛋白（前VLDL）体积太大，无法装入传统的COPII被膜小泡，那么这些大分子货物是如何从内质网（ER）输出的呢？我们已经表明，位于内质网出口位点的TANGO1对于前胶原蛋白的输出是必需的。我们报道了TANGO1和类TANGO1（TALI）的作用，TALI是一种由MIA2和cTAGE5基因产物融合产生的嵌合蛋白，在前乳糜微粒和前VLDL从内质网的输出中发挥作用。TANGO1与TALI结合，二者都与载脂蛋白B（ApoB）相互作用，并且对于将含ApoB的脂质颗粒募集到内质网出口位点以便随后输出是必需的。虽然ApoB的输出需要TANGO1和TALI二者的功能，但同一细胞中前胶原蛋白XII的输出仅需要TANGO1。这些发现揭示了TANGO1在内质网大分子货物输出中的普遍作用，并确定了TALI在协助TANGO1输出大分子脂质颗粒方面的特定需求。
