| Structural highlights
Disease
[U119A_HUMAN] Idiopathic CD4 lymphocytopenia;Cone rod dystrophy. Defects in UNC119 may be a cause of cone-rod dystrophy. A mutation was found in a 57-year-old woman with late-onset cone-rod dystrophy: from 40 year old, the patient suffered from poor night vision, defective color vision and light-sensitivity. At 57 year old, she displayed reduced visual acuity, myopa, macular atrophy and pericentral ring scotomas. The disease was caused by a heterozygous mutation causing premature termination and truncated UNC119 protein with dominant-negative effect.
Function
[U119A_HUMAN] Myristoyl-binding protein that acts as a cargo adapter: specifically binds the myristoyl moiety of a subset of N-terminally myristoylated proteins and is required for their localization. Binds myristoylated GNAT1 and is required for G-protein localization and trafficking in sensory neurons. Binds myristoylated NPHP3; however, in contrast to UNC119B, does not seem to play a major role in ciliary membrane localization of NPHP3. Does not bind all myristoylated proteins. Probably plays a role in trafficking proteins in photoreceptor cells.[1] [2]
Publication Abstract from PubMed
Upon engagement of the T cell receptor with an antigen-presenting cell, LCK initiates TCR signaling by phosphorylating its activation motifs. However, the mechanism of LCK activation specifically at the immune synapse is a major question. We show that phosphorylation of the LCK activating Y394, despite modestly increasing its catalytic rate, dramatically focuses LCK localization to the immune synapse. We describe a trafficking mechanism whereby UNC119A extracts membrane-bound LCK by sequestering the hydrophobic myristoyl group, followed by release at the target membrane under the control of the ciliary ARL3/ARL13B. The UNC119A N terminus acts as a "regulatory arm" by binding the LCK kinase domain, an interaction inhibited by LCK Y394 phosphorylation, thus together with the ARL3/ARL13B machinery ensuring immune synapse focusing of active LCK. We propose that the ciliary machinery has been repurposed by T cells to generate and maintain polarized segregation of signals such as activated LCK at the immune synapse.
The Ciliary Machinery Is Repurposed for T Cell Immune Synapse Trafficking of LCK.,Stephen LA, ElMaghloob Y, McIlwraith MJ, Yelland T, Castro Sanchez P, Roda-Navarro P, Ismail S Dev Cell. 2018 Oct 8;47(1):122-132.e4. doi: 10.1016/j.devcel.2018.08.012. Epub, 2018 Sep 13. PMID:30220567[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wright KJ, Baye LM, Olivier-Mason A, Mukhopadhyay S, Sang L, Kwong M, Wang W, Pretorius PR, Sheffield VC, Sengupta P, Slusarski DC, Jackson PK. An ARL3-UNC119-RP2 GTPase cycle targets myristoylated NPHP3 to the primary cilium. Genes Dev. 2011 Nov 15;25(22):2347-60. doi: 10.1101/gad.173054.111. PMID:22085962 doi:10.1101/gad.173443.111
- ↑ Zhang H, Constantine R, Vorobiev S, Chen Y, Seetharaman J, Huang YJ, Xiao R, Montelione GT, Gerstner CD, Davis MW, Inana G, Whitby FG, Jorgensen EM, Hill CP, Tong L, Baehr W. UNC119 is required for G protein trafficking in sensory neurons. Nat Neurosci. 2011 Jun 5. PMID:21642972 doi:10.1038/nn.2835
- ↑ Stephen LA, ElMaghloob Y, McIlwraith MJ, Yelland T, Castro Sanchez P, Roda-Navarro P, Ismail S. The Ciliary Machinery Is Repurposed for T Cell Immune Synapse Trafficking of LCK. Dev Cell. 2018 Oct 8;47(1):122-132.e4. doi: 10.1016/j.devcel.2018.08.012. Epub, 2018 Sep 13. PMID:30220567 doi:http://dx.doi.org/10.1016/j.devcel.2018.08.012
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