Fig. 6: Dimerized key arginine residues in the intracellular domain play a critical role in PD-L1 complex glycosylation.
From: Homodimerized cytoplasmic domain of PD-L1 regulates its complex glycosylation in living cells
a PD-L1-3RE mutant suppresses complex glycosylation of WT PD-L1. PD-L1-HA plasmid was cotransfected with PD-L1-3RE-Flag or PD-L1△C-Flag into RKO KO PD-L1 cells. b Plasma membrane localization of WT PD-L1 attenuates in cells expressing PD-L1-3RE mutant. Shown are immunofluorescence of cells expressing PD-L1-HA and PD-L1-3RE-Flag/PD-L1△C-Flag. Representative images are shown for each condition. Scale bars, 5 μm. c Total expression level of WT PD-L1 decreased in cells expressing PD-L1-3RE. RKO KO PD-L1 cells were transfected with PD-L1-HA or cotransfected with PD-L1-HA and PD-L1-3RE-Flag. Samples of lanes 3–4 were de-glycosylated with PNGase F. d, e PD-L1-3RE stabilized highly mannosylated PD-L1. PD-L1-HA or PD-L1-HA and PD-L1-3RE-Flag were transfected into RKO KO PD-L1 cells. The duration that cells treated with 150 µM CHX was labeled at the upper row. The quantification data represent the mean ± SEM for three independent experiments. *P ≤ 0.05, **P ≤ 0.01. f Effect of 3RE mutation on conformation of the PD-L1 ECD homodimer. Samples were treated with PNGase F to remove the N-glycan.
