Early endosomes (EE) provide the starting point for late endosome maturation. The EEs are mainly derived

from primary endocytic vesicles that fuse with each other. EEs receive endocytic cargo not only through the

clathrin-mediated pathway but several other pathways. In addition to their roles in normal cell physiology,

endocytic processes play a key role in many diseases such as Alzheimer’s disease and inherited

lysosomal storage diseases. Traditional methods for isolating endosomesare based on density gradient

ultracentrifugation. The protocol requires large amount of starting material and the methods are tedious and

time consuming. The minute Endosome Isolation and Cell Fractionation Kit provides a spin-column based

novel endosome isolation technology that is rapid, simple and requires smaller number of cultured cells or

milligram amounts of tissues. This kit can precipitate and significantly enrich early endosomes from cultured

cells or tissues. The availability of the kit should facilitatethe research in the field.

Enrichment of endosomes. Endosomes were isolated from mouse kidney tissue as described in the

protocol. Total cellular protein(T) and endosomes(E) in duplicate were separated in 12% SDS-PAGE. After

electrical trasnfer, the membrane was stained with Ponceau Red(A). The blot was probed with early

endosome antigen1, Na/K ATPase and tubulin by Western blotting(B).