Endosomes are formed by the invagination of the plasma membrane and are triggered by the activation of cell surface receptors (Hurley, 2008). Endosomes control the sorting of activated cell surface receptors either to the plasma membrane for further use or to the lysosome for degradation.

How does an endosome become a lysosome?

Substances targeted for lysosomal degradation are transferred from early endosomes to late endosomes by endocytic carrier vesicles. Transport vesicles that carry lysosomal hydrolases from the trans-Golgi network (TGN) then fuse with late endosomes, leading to maturation of late endosomes into lysosomes.

What is endosomes and its function?

Endosomes are primarily intracellular sorting organelles. They regulate trafficking of proteins and lipids among other subcellular compartments of the secretory and endocytic pathway, specifically the plasma membrane Golgi, trans-Golgi network (TGN), and vacuoles/lysosomes.