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Updated: Jun 1, 2026
Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes
Published on: March 14, 2021
Phosphotyrosine phosphatase-activity in membranes from endometrial carcinoma
Abstract:
The phosphotyrosine phosphatase (PTPase) decreases the level of phosphotyrosine of intracellular protein substrates, thereby reversing the action of tyrosine phosphorylation to promote cell growth and differentiation. We determined the activities of PTPases in normal and cancerous tissues of the endometrium. The PTPase activity was determined with the synthetic substrate p-nitrophenyl in a spectrophotometric assay. Over 90% of the activity was particulate and the values in proliferative- and secretory-phase endometria and endometrial carcinomas fell within a similar range. This work demonstrates the existence of PTPase activity, counterbalancing the growth-promoting effects of tyrosine kinases, in endometrial carcinoma.
Insights
Phosphotyrosine phosphatase (PTPase) activity was measured in normal and cancerous endometrial tissues. PTPase activity was found to be similar across proliferative, secretory, and cancerous endometria, suggesting a role in counterbalancing cell growth.
Area of Science:
- Biochemistry
- Molecular Biology
- Gynecologic Oncology
Background:
- Phosphotyrosine phosphatases (PTPases) regulate cellular processes by dephosphorylating tyrosine residues on proteins.
- Tyrosine phosphorylation, mediated by tyrosine kinases, is crucial for cell growth and differentiation.
- Dysregulation of PTPase activity is implicated in various cancers, including endometrial carcinoma.
Purpose of the Study:
- To determine and characterize phosphotyrosine phosphatase (PTPase) activity in normal and cancerous endometrial tissues.
- To investigate the potential role of PTPase activity in the context of endometrial carcinoma.
Main Methods:
- PTPase activity was quantified using a spectrophotometric assay with the synthetic substrate p-nitrophenyl.
- Enzyme activity was assessed in both normal (proliferative and secretory phase) and cancerous endometrial tissues.
- The subcellular localization of PTPase activity was investigated.
Main Results:
- Over 90% of the measured PTPase activity was found to be associated with cellular particulates.
- PTPase activity levels were comparable across proliferative endometria, secretory endometria, and endometrial carcinomas.
- This indicates a consistent presence of PTPase activity in both healthy and malignant endometrial tissue.
Conclusions:
- The study demonstrates the presence of phosphotyrosine phosphatase (PTPase) activity in endometrial carcinoma.
- This PTPase activity appears to counterbalance the growth-promoting effects of tyrosine kinases in endometrial cancer.
- Further research into PTPase function may reveal therapeutic targets for endometrial cancer.
