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Fig. 8. SKD1 functions in mammalian endosomal/lysosomal systems at multiple steps
in membrane transport. A schematic diagram represents the stages of membrane
transport that are inhibited by the overexpression of SKD1(E235Q). (A)
SKD1(E235Q)-expression inhibits the early endosomal recycling of TfR, LDLR and
ASGPR to the PM as well as of TGN38 and MPR to the TGN. EGFR downregulation
was suppressed by the inhibition of either the vesicle transport from early to
late endosomes or the maturation (multivesicular formation?) of the early
endosome into a late endosome. (B) SKD1(E235Q)-expression may inhibit the
reformation of lysosomes from the hybrid organelles. This defect leads to the
accumulation of hybrid organelles.