Fig. 2: Ca2+ signals induce phosphorylation, polyubiquitination and proteasomal degradation of Arpp21. | Nature Communications

Fig. 2: Ca2+ signals induce phosphorylation, polyubiquitination and proteasomal degradation of Arpp21.

From: The thymocyte-specific RNA-binding protein Arpp21 provides TCR repertoire diversity by binding to the 3’-UTR and promoting Rag1 mRNA expression

Fig. 2

Immunoblot analyses of Arpp21 and indicated loading controls in extracts of thymocytes from (a) TCR-transgenic OTI, Stim1fl/fl;Stim2fl/fl;Vav-iCre (g) or Camk4–/– (h) as well as WT mice (b–h). Cells were stimulated with (a) 2 µg/mL of cognate peptide SIINFEKL or (b) 1 µg/mL of anti-CD3 and 2 µg/mL anti-CD28 for 0 h, 1 h, 2 h and 3 h or (c–h) with 1 µM ionomycin or (c) 20 nM PMA or (d–f) 10 μM MG132, as indicated. e, f Protein extracts from WT mice stimulated with ionomycin and MG-132 were immunoprecipitated with Arpp21-specific antibodies, separated by SDS-PAGE and probed with ubiquitin-reactive antibodies or treated with phosphatase buffer and with antarctic phosphatase to analyze Arpp21 mobility in SDS-PAGE as detected by immunoblotting. Each experiment was performed at least twice. Source data for (a–h) are provided as a Source Data file.

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