Fig. 5

LAMP3 directly interacted with RPL21 and enhanced the stability of the RPL21 protein. A RPL21 and LAMP3 were immunoprecipitated in HCT-8 cells detected by western blotting. B Direct binding of RPL21-GST and LAMP3-6His using the His pull-down assay. The pull-down bands were detected by Coomassie brilliant blue staining and western blotting. C Topology of LAMP3, including the luminal segment (aa 1–381), the transmembrane segment (aa 382–406), and the cytoplasmic segment (aa 407–416). Diagrammatic representation of RPL21 and LAMP3 with their truncated/deleted mutation forms. D–F HEK293T cells were transfected with the indicated constructs and immunoprecipitated with anti-6His (D) or anti-GST (E, F). The red boxes represent the pull-down bands detected by western blotting. G LAMP3 and RPL21 protein expression in the indicated cells was detected by western blotting. H The degradation of the RPL21 protein in HCT15 Ctrl, HCT15 LAMP3, HCT-8 siCtrl, and HCT-8 siLAMP3 cells with CHX treatment (50 μg/mL) was detected by western blotting. The quantification of the protein level was normalized to that of GAPDH. Mean ± SD, n = 3, ***p < 0.001, Student’s t-test. I LAMP3 and RPL21 protein expression in HCT-8 siCtrl, HCT-8 siLAMP3, and HCT-8 siLAMP3 cells treated with MG132 (10 μM, 4 h) or CQ (50 μM, 2 h) was detected by western blotting