TCDB is operated by the Saier Lab Bioinformatics Group

8.A.74 The TM9 or Phg1 Targeting Receptor (Ppg1) Family 

TM9 family proteins (also named Phg1 proteins) control cell adhesion by determining the cell surface localization of adhesion proteins such as the Dictyostelium SibA protein. Perrin et al. 2015 showed that the glycine-rich transmembrane segments (TMSs) of SibA is sufficient to confer Phg1A-dependent surface targeting to a reporter protein. In Dictyostelium phg1A- knockout (KO) cells, proteins with glycine-rich TMSs were less efficiently transported out of the endoplasmic reticulum (ER) and to the cell surface. Phg1A, as well as its human ortholog TM9SF4 specifically associated with glycine-rich TMSs. In human cells, genetic inactivation of TM9SF4 resulted in an increased retention of glycine-rich TMSs in the endoplasmic reticulum, whereas TM9SF4 overexpression enhanced their surface localization. The bulk of the TM9SF4 protein was localized in the Golgi complex, and a proximity-ligation assay suggested that it might interact with glycine-rich TMSs. It thus appears that one of the main roles of TM9 proteins is to serve as intramembrane cargo receptors controlling exocytosis and surface localization of a subset of membrane proteins.

References associated with 8.A.74 family:

Gery, S., D. Yin, D. Xie, K.L. Black, and H.P. Koeffler. (2003). TMEFF1 and brain tumors. Oncogene 22: 2723-2727. 12743596
Hudlikar, R.R., D. Sargsyan, W. Li, R. Wu, M. Zheng, and A.N. Kong. (2021). Epigenomic, Transcriptomic, and Protective Effect of Carotenoid Fucoxanthin in High Glucose-Induced Oxidative Stress in Mes13 Kidney Mesangial Cells. Chem Res Toxicol. [Epub: Ahead of Print] 33448797
Huzé, C., S. Bauché, P. Richard, F. Chevessier, E. Goillot, K. Gaudon, A. Ben Ammar, A. Chaboud, I. Grosjean, H.A. Lecuyer, V. Bernard, A. Rouche, N. Alexandri, T. Kuntzer, M. Fardeau, E. Fournier, A. Brancaccio, M.A. Rüegg, J. Koenig, B. Eymard, L. Schaeffer, and D. Hantaï. (2009). Identification of an agrin mutation that causes congenital myasthenia and affects synapse function. Am J Hum Genet 85: 155-167. 19631309
Koppel, N., M.B. Friese, H.L. Cardasis, T.A. Neubert, and S.J. Burden. (2019). Vezatin is required for the maturation of the neuromuscular synapse. Mol. Biol. Cell 30: 2571-2583. 31411944
Lee, S.J., T. Uemura, T. Yoshida, and M. Mishina. (2012). GluRδ2 assembles four neurexins into trans-synaptic triad to trigger synapse formation. J. Neurosci. 32: 4688-4701. 22457515
Lok, H.C. and J.B. Kwok. (2021). The Role of White Matter Dysfunction and Leukoencephalopathy/Leukodystrophy Genes in the Aetiology of Frontotemporal Dementias: Implications for Novel Approaches to Therapeutics. Int J Mol Sci 22:. 33802612
Matsuda, K. (2016). Synapse organization and modulation via C1q family proteins and their receptors in the central nervous system. Neurosci Res. [Epub: Ahead of Print] 27845167
Perrin, J., M. Le Coadic, A. Vernay, M. Dias, N. Gopaldass, H. Ouertatani-Sakouhi, and P. Cosson. (2015). TM9 family proteins control surface targeting of glycine-rich transmembrane domains. J Cell Sci 128: 2269-2277. 25999474
Zhang, W., A.S. Coldefy, S.R. Hubbard, and S.J. Burden. (2011). Agrin binds to the N-terminal region of Lrp4 protein and stimulates association between Lrp4 and the first immunoglobulin-like domain in muscle-specific kinase (MuSK). J. Biol. Chem. 286: 40624-40630. 21969364