FIGURE 6.

Proposed role of ABHD6 in the late endosomal/lysosomal pathway. Endocytic vesicles form early endosomes in the peripheral cytoplasm that move toward the perinuclear area along microtubuli. Their conversion into LE involves the formation of BMP-containing ILVs. LE finally fuse with lysosomes to form endolysosomes (51). BMP is resistant to acid hydrolysis and forms stable membrane structures within acidic organelles, promoting lipid digestion and sorting. BMP-rich ILVs of LE and endolysosomes can fuse with the limiting membrane, allowing the export of ILV contents. After back-fusion, BMP appears on the limiting membrane and is degraded by ABHD6 into LPG and FFA. Additionally, ABHD6 may counteract de novo BMP synthesis on the limiting membrane of LE.