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High-yield isolation of functionally competent endosomes from mouse lymphocytes.
1Department of Biochemistry, Imperial College of Science and Technology, London, U.K.
The Biochemical Journal
|November 15, 1989
Summary
Researchers developed a new method to isolate functional endosomes from mouse lymphoma cells. This technique improves endosome recovery and purity, enabling further study of endosome fusion and acidification processes.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Endosomes play a crucial role in cellular transport and signaling.
- Efficient isolation of pure, functional endosomes is essential for studying their properties.
Purpose of the Study:
- To develop a novel, high-yield method for isolating endosomes from mouse lymphoma cells.
- To characterize the purity and functionality of the isolated endosomes.
Main Methods:
- Discontinuous sucrose gradient centrifugation of mouse lymphoma cell lysates.
- Optimization using trypsin treatment and low-density lipoprotein loading.
- Plasma membrane removal via gold-ricin complex pre-incubation.
- Functional assays including fusion (using fluorescence resonance energy transfer) and acidification.
Main Results:
- Achieved a 100% increase in endosome recovery with optimized methods.
- Isolated endosomes showed <6% contamination by other organelles.
- Isolated endosomes retained 42% of internalized 125I-transferrin.
- Demonstrated cell-free endosome fusion dependent on ATP and a cytosolic protein factor.
Conclusions:
- The developed method provides a pure and functional endosome preparation.
- Isolated endosomes are capable of ATP-dependent fusion, mediated by cytosolic factors.
- Early endosomes exhibit distinct fusion dynamics compared to late endocytic vesicles.