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Rat skeletal muscle lysosomes contain glycogen
1Department of Biochemistry, University of Auckland, New Zealand.
The International Journal of Biochemistry
|January 1, 1989
Summary
Skeletal muscle lysosomes contain significant glycogen stores, suggesting a role in glycogen metabolism compartmentation. This finding highlights the importance of lysosomes beyond their known degradative functions.
Area of Science:
- Biochemistry
- Cell Biology
- Muscle Physiology
Background:
- Skeletal muscle glycogen serves as a primary energy source.
- Glycogen metabolism is primarily associated with the cytoplasm and sarcoplasmic reticulum.
Purpose of the Study:
- To investigate the subcellular localization of glycogen within rat skeletal muscle.
- To determine if glycogen is associated with specific organelles, such as lysosomes and mitochondria.
Main Methods:
- Differential centrifugation was used to isolate lysosome- and mitochondria-enriched fractions from rat skeletal muscle.
- Ficoll-sucrose density gradients were employed to separate lysosomes and mitochondria.
- Glycogen content in isolated fractions was quantified.
Main Results:
- A lysosome- and mitochondria-enriched fraction contained 3-4% of total skeletal muscle glycogen.
- Separation of lysosomes and mitochondria revealed that lysosomes, not mitochondria, contained significant glycogen (5% of total).
- Purified lysosomal glycogen was enriched in high molecular weight components.
Conclusions:
- Skeletal muscle glycogen is compartmentalized within lysosomes.
- Lysosomes may play a direct role in skeletal muscle glycogen metabolism.
- These findings suggest a novel function for lysosomes in energy storage and utilization.