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8.A.86 The Chloroplast Trigalactosyldiacylglycerol-5 (TGD5) Protein Family. 

TGD5 facilitates lipid transfer from the outer to the inner plastid envelope by bridging TGD4 (TC# 1.B.82.1.1) with the TGD1,2,3 transport complex (3.A. TGD5 is required for endoplasmic reticulum-to-plastid lipid trafficking as part of the eukaryotic pathway of thylakoid lipid assembly (Fan et al. 2015).  Disruption of TGD5 results in phenotypic effects similar  to those for tgd1,2,3,4 mutants, including deficiency of ER-derived thylakoid lipids, accumulation of oligogalactolipids, and triacylglycerol. Genetic analysis indicated that TGD4 is epistatic to TGD5 in ER-to-plastid lipid trafficking, whereas double mutants of a null tgd5 allele with tgd1-1 or tgd2-1 showed a synergistic embryo-lethal phenotype. TGD5 is a small glycine-rich protein that is localized in the envelope membranes of chloroplasts. Coimmunoprecipitation assays suggested that TGD5 physically interacts with TGD1, TGD2, TGD3, and TGD4. Collectively, these results suggest that TGD5 facilitates lipid transfer from the outer to the inner plastid envelope by bridging TGD4 with the TGD1,2,3 transporter complex (Fan et al. 2015).

References associated with 8.A.86 family:

Fan, J., Z. Zhai, C. Yan, and C. Xu. (2015). Arabidopsis TRIGALACTOSYLDIACYLGLYCEROL5 Interacts with TGD1, TGD2, and TGD4 to Facilitate Lipid Transfer from the Endoplasmic Reticulum to Plastids. Plant Cell 27: 2941-2955. 26410300
Paolillo, R., I. Spinello, M.T. Quaranta, L. Pasquini, E. Pelosi, F. Lo Coco, U. Testa, and C. Labbaye. (2015). Human TM9SF4 Is a New Gene Down-Regulated by Hypoxia and Involved in Cell Adhesion of Leukemic Cells. PLoS One 10: e0126968. 25961573
Perrin, J., M. Mortier, A.C. Jacomin, P. Viargues, D. Thevenon, and M.O. Fauvarque. (2015). The nonaspanins TM9SF2 and TM9SF4 regulate the plasma membrane localization and signalling activity of the peptidoglycan recognition protein PGRP-LC in Drosophila. J Innate Immun 7: 37-46. 25139117
Pruvot, B., V. Laurens, F. Salvadori, E. Solary, L. Pichon, and J. Chluba. (2010). Comparative analysis of nonaspanin protein sequences and expression studies in zebrafish. Immunogenetics 62: 681-699. 20820770
Sun, L., Z. Meng, Y. Zhu, J. Lu, Z. Li, Q. Zhao, Y. Huang, L. Jiang, and X. Yao. (2018). TM9SF4 is a novel factor promoting autophagic flux under amino acid starvation. Cell Death Differ 25: 368-379. 29125601