Lysosome

The acidic compartment that digests what the cell takes in or breaks down, and reports on the state of metabolism while it does.

Lumen pH

Between 4.5 and 5.0. The hydrolases inside are activated by that acidity.

review · review · Mindell JA 2012, Annu Rev Physiol · source

How it acidifies

A proton-pumping V-type ATPase uses ATP to pump protons into the lumen; a counterion must move to dissipate the voltage, and the chloride and proton antiporter ClC-7 is implicated in that step.

review · review · Mindell JA 2012, Annu Rev Physiol · source

Markers

LAMP-1 and LAMP-2 are widely used as lysosomal markers; they also inhibit the cation channel TMEM175 and so help the organelle reach the lower pH its hydrolases need.

human · proteomics, cryo-EM, electrophysiology and imaging · Zhang J et al. 2023, Mol Cell · source

Beyond digestion

It also works as a signalling hub, sensing the state of metabolism and controlling the switch between anabolism and catabolism; its dysfunction runs from lysosomal storage disorders to common neurodegenerative and metabolic disease.

review · review · Ballabio A, Bonifacino JS 2020, Nat Rev Mol Cell Biol · source

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Number per cell

No sourced value for this yet: lysosome number varies with cell type and with autophagic state, and no verified abstract gives a figure that would hold across the network's cells.

An electron micrograph of this organelle

Searched and not found under a licence the owner's rules allow. Wikimedia Commons holds only videos and molecular models for it, and the closest open-access paper found (PMC13329886) is CC BY-NC-SA, which is outside the limits. The EM volume on hand, EMPIAR-10791, segments ER, mitochondria, lipid droplet and membranes but not this organelle. This is a finished search with a negative result, not an outstanding task.

Behind the copy

The lysosome disposes of and recycles cellular waste and also works as a signalling hub, sensing the state of metabolism and controlling the switch between anabolism and catabolism; its dysfunction runs from lysosomal storage disorders to common neurodegenerative and metabolic disease. Phagosomes mature by fusing with acidic, hydrolase-rich lysosomes, whose lumen is acidified by the vacuolar ATPase.

source 1, source 2

Other organelles

All · Autophagosome · Centrosome · Cilia and flagella · Cytoskeleton · Endosomes and vesicles · Golgi · Lipid droplet · Mitochondrion · Nuclear envelope · Nucleolus · Nucleus · Peroxisome · Plasma membrane · Proteasome · Ribosome · Rough ER · Smooth endoplasmic reticulum

Building the copy.