The article discusses the maturation of late endosomes (LEs) in mammalian cells, which are also known as multivesicular bodies (MVBs). LEs are formed from the vacuolar domains of early endosomes (EEs) and undergo a series of transformations to become functional organelles that deliver cargo to lysosomes. The maturation process involves a Rab GTPase switch from Rab5 to Rab7, which reprograms the endosomal membrane and enables the LEs to fuse with lysosomes. The maturation programme includes the formation of intralumenal vesicles (ILVs), acidification, changes in membrane composition, and the acquisition of lysosomal components. The process is tightly regulated and involves various proteins and lipid modifications, including the conversion of phosphatidylinositol (PI) species. The article also highlights the role of the ESCRT machinery in ILV formation and the importance of Rab5/Rab7 conversion in endosome maturation. The maturation of LEs is essential for the degradation of internalized cargo and the maintenance of lysosomal function. The study provides insights into the complex molecular mechanisms underlying endosome maturation and its role in cellular processes such as endocytosis, recycling, and degradation.The article discusses the maturation of late endosomes (LEs) in mammalian cells, which are also known as multivesicular bodies (MVBs). LEs are formed from the vacuolar domains of early endosomes (EEs) and undergo a series of transformations to become functional organelles that deliver cargo to lysosomes. The maturation process involves a Rab GTPase switch from Rab5 to Rab7, which reprograms the endosomal membrane and enables the LEs to fuse with lysosomes. The maturation programme includes the formation of intralumenal vesicles (ILVs), acidification, changes in membrane composition, and the acquisition of lysosomal components. The process is tightly regulated and involves various proteins and lipid modifications, including the conversion of phosphatidylinositol (PI) species. The article also highlights the role of the ESCRT machinery in ILV formation and the importance of Rab5/Rab7 conversion in endosome maturation. The maturation of LEs is essential for the degradation of internalized cargo and the maintenance of lysosomal function. The study provides insights into the complex molecular mechanisms underlying endosome maturation and its role in cellular processes such as endocytosis, recycling, and degradation.