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Cytosolic protein-tyrosine kinase activities in various rat tissues
T Kobayashi1, S Nakamura, H Yamamura
1Department of Biochemistry, Fukui Medical School, Japan.
Abstract:
Suitable assay conditions for the detection of cytosolic protein-tyrosine kinase activities in crude extracts of various rat tissues have been determined. Cytosolic protein-tyrosine kinases showed common characteristics including substrate specificity and divalent cation requirement. Using (Val5) angiotensin II and Mn2+ rather than a src-related synthetic peptide, E11G1, and Mg2+, we obtained higher activities of cytosolic protein-tyrosine kinases. Among various rat tissues tested, spleen, bone marrow, thymus, small intestine, appendix and lung, in decreasing order of total activity, contained high activities of cytosolic protein-tyrosine kinases. These results suggest that the enzyme activities in lymphatic organs and in organs closely related to cell proliferation are high. The assay system described allows the precise measurement of cytosolic protein-tyrosine kinase activity in various rat tissues, both normal and malignant.
Insights
Assay conditions were optimized to detect cytosolic protein-tyrosine kinase activity in rat tissues. Spleen, bone marrow, and thymus showed the highest enzyme activities, indicating their importance in cell proliferation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Signaling
Background:
- Cytosolic protein-tyrosine kinases are crucial enzymes involved in cellular signaling pathways.
- Understanding their activity in different tissues is essential for comprehending normal physiology and disease states.
Purpose of the Study:
- To establish optimal assay conditions for measuring cytosolic protein-tyrosine kinase activity in crude rat tissue extracts.
- To identify rat tissues with high cytosolic protein-tyrosine kinase activity.
Main Methods:
- Determination of suitable assay conditions, including substrate specificity and divalent cation requirements.
- Utilized (Val5) angiotensin II and Mn2+ for enhanced detection of enzyme activity.
- Assayed activity across various rat tissues, including spleen, bone marrow, thymus, small intestine, appendix, and lung.
Main Results:
- Cytosolic protein-tyrosine kinases exhibit common characteristics such as substrate specificity and divalent cation dependence.
- Employing (Val5) angiotensin II and Mn2+ yielded higher enzyme activities compared to src-related peptide and Mg2+.
- Spleen, bone marrow, thymus, small intestine, appendix, and lung demonstrated the highest cytosolic protein-tyrosine kinase activities, in descending order.
Conclusions:
- The developed assay system enables precise measurement of cytosolic protein-tyrosine kinase activity in diverse rat tissues.
- High enzyme activities are observed in lymphatic organs and tissues associated with cell proliferation.
- These findings provide a foundation for further research into the role of these kinases in normal and malignant tissues.