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Subcellular fractionation studies indicate an intracellular localization for human monocyte specific esterase (MSE)
D Patel1, N M Hooper, C S Scott
1Haematological Malignancy Diagnostic Service, Cookridge Hospital, Leeds.
British Journal of Haematology
|August 1, 1993
Summary
Human monocyte-specific esterase (MSE) is not a plasma membrane enzyme as previously thought. New research indicates MSE is a soluble intracellular enzyme, likely located within the endoplasmic reticulum lumen.
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Human monocyte-specific esterase (MSE) is a haemopoietic cell enzyme with restricted lineage expression.
- Its function remains unknown, but its potential role in tumor cell killing is of significant interest.
- Previous studies suggested MSE is a plasma membrane ectoenzyme based on ultrastructural cytochemistry of fixed cells.
Purpose of the Study:
- To investigate the subcellular localization of human monocyte-specific esterase (MSE).
- To determine if MSE is membrane-bound or associated with an intracellular organelle.
- To reconcile inconsistencies between MSE's structure and previously proposed membrane localization.
Main Methods:
- Phase separation using the non-ionic detergent Triton X-114.
- Differential centrifugation techniques.
- Analysis of enzyme localization in cellular fractions.
Main Results:
- Evidence strongly suggests MSE is a soluble intracellular enzyme.
- MSE is most likely located within the lumen of the endoplasmic reticulum.
- Findings contradict the widely held belief of MSE as a plasma membrane ectoenzyme.
Conclusions:
- Human monocyte-specific esterase (MSE) is an intracellular enzyme, not a plasma membrane ectoenzyme.
- The endoplasmic reticulum lumen is the probable location for MSE.
- This revised localization is crucial for understanding MSE's function and potential roles.