Journal: bioRxiv
Article Title: An ER Retrieval-and-Release System Reveals Ligand-Independent Basal Signaling by Cell Surface TCRs
doi: 10.64898/2026.10.13.758962
Figure Lengend Snippet: (A) JKεKO KDEL-εRUSH cells were cultured for one hour with (+ biotin) or without biotin. After cell lysis, peptides were generated using trypsin. Phospho-peptides were enriched and identified by tandem mass spectrometry. Their intensities in the +biotin condition were compared with those without biotin treatment and visualized as volcano plot based on moderated t-tests. Phosphorylations significantly enriched, p-value <0.05 and log 2 fold change >1.0, are shown in green and the ones enriched without biotin in brown. The black dots represent Y phosphorylations significantly changed in one condition. (B) All phospho-Y peptides enriched in the + biotin sample from (A) are shown. Sites known to be induced by ligand binding to the TCR are indicated in the “by TCR ligand” column and the ones known to have an activatory role in ligand-induced TCR signaling in the “activation” column. (C) JKεKO KDEL-εRUSH cells were cultured for one hour with (+ biotin) and left unstimulated or stimulated for 5 min with anti-CD3ε antibodies. Phosphoproteomics and display as in (A) comparing the +/- TCR stimulation conditions. (D) Comparison of the basal TCR signal (phosphopeptides from JKεKO KDEL-εRUSH cells with biotin for 1 h versus without biotin, X axis) with the activation signal (phosphopeptides from JKεKO KDEL-εRUSH cells with biotin and stimulated for 5 min with anti-CD3 antibodies versus unstimulated, Y axis). Phosphopeptides significantly enriched both in the basal TCR signature (Table S4) and with the activation signal are shown in purple, those depleted in the basal signal and enriched in the activation signal in blue, those enriched in the basal signal and depleted in the activation signal in cyan, and all others in grey.
Article Snippet: For functional assessment, CD3ε-ERR and control mock T cells were stimulated with plate-bound anti-CD3 (clone OKT3; Miltenyi Biotec), as previously described .
Techniques: Cell Culture, Lysis, Generated, Mass Spectrometry, Ligand Binding Assay, Activation Assay, Phospho-proteomics, Comparison, Significance Assay