Fig. 1: FRTACs mediate the uptake and lysosomal degradation of soluble proteins.

a Illustration of FRTAC-induced lysosomal targeted protein degradation. b Generation of FRTAC through a two-step labeling method. c Schematic of mouse anti-FITC uptake mediated by Ab-FA and FA-FITC. d Uptake of anti-FITC-594 (50 nM) in HepG2 cells treated with Ab-FA (25 nM) and FA-FITC (200 nM) for 3 h (n = 3). e In-gel fluorescence analysis of anti-biotin-647 (50 nM) internalization and degradation in HepG2 cells by Ab-FA (25 nM) in the presence or absence of Chloroquine (CQ, 20 μM), Bafilomycin A1 (BAF, 200 nM), and MG132 (1 μM) for 24 h (n = 3). f Cellular uptake and lysosome colocalization of anti-Rabbit-647 (50 nM) in the presence of Ab (25 nM), Ab (25 nM) + free FA (125 nM), and Ab-FA (25 nM) in Hela cells for 24 h by immunofluorescent staining. Scale bar: 50 μm. The colocalization of internalized anti-Rabbit-647 with lysosomes was analyzed by Pearson’s correlation coefficients. The intracellular fluorescence intensity is presented as mean fluorescence intensity (MFI) (n = 15 images from three biologically independent experiments). Box plot: minima (lower whisker), maxima (upper whisker), center (median), bounds of the box (25th and 75th percentiles), whiskers (range from minima to maxima). g. Uptake of anti-Rabbit-647 (50 nM) mediated by Ab-FA (25 nM) in Hela cells transfected with scramble siRNA or Rab7 siRNA for 3 h (n = 3). N indicates biologically independent experiments except for Fig. 2f. Data are presented as mean ± SD. The statistical significance was assessed using an unpaired two-tailed t test, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, ns: not significant. Source data are provided as a Source Data file.