Lysosomal enzymes
from Golgi
H+ pump
Exogenous waste
imported by
of endocytosis
Endogenous waste : proteins,
nucleic acids, lipids, sulfates, phosphates,
sterols, sugars, deteriorated mitochondria
Single layer
Lysosomes, present in nearly all cells, are their key waste disposal route, both for endogenous and exogenous substances (by trafficking of endocytosis vesicles ; deficient trafficking of exogenous cholesterol towards lysosomes leads to Niemann Pick C & D).
Lysosomes owe their efficacy to :
- their excellent out to in permeability (single layer membrane*)
- the low pH at which their enzymes are active, maintained by a H+ pump
- the constant arrival of enzymes produced by the reticulum and "addressed" by the Golgi.
Absence of one of these enzymes, albeit direct consequences of non metabolism of the substrate, leads to lysosomal accumulation of this substrate, puffing up the lysosomes, and severely compromising cell function
Lysosomes : cellular waste disposal
For more info, click on the underlined links below :
* Only one other cell organelle has a single layer membrane : the peroxysome. X linked adrenoleukodystrophy appears when it lacks the capacity to metabolize fatty acids
Lysosomal diseases
Ceramides & Sphingolipids
Biosynthesis of lysosomes
Mannose 6 Phosphate & recognition of lysosomal enzymes
Lysosomes, cellular waste disposal facilities
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