Assessment of mammalian endosomal microautophagy

Endosomal microautophagy (eMI) involves the selective uptake and degradation of proteins in late endosome/multi-vesicular bodies.

• eMI initiates with the recognition of a specific pentapeptide motif in substrate proteins by the hsc70 chaperone.
• This recognition allows for the binding and uptake of proteins into the late endosome/multi-vesicular body compartment.
• The process shares a critical initial step with chaperone-mediated autophagy (CMA), complicating the differentiation between the two pathways.
• Biochemical and imaging-based methods are detailed for tracking eMI activity in vitro and in cultured cells.
• Approaches are highlighted to determine whether a protein is a substrate of eMI or CMA.

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