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Recombinants within the tyrosine kinase region of v-abl and v-src identify a v-abl segment that confers lymphoid
1Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142.
Abstract:
The v-abl and v-src oncogenes encode protein-tyrosine kinases that possess different biological properties in spite of their high degree of amino acid conservation. To correlate functional differences with structural domains of the two oncogenes, we recombined v-abl and v-src just downstream of the lysines in their ATP-binding sites, within the kinase domain. The biological activity of the chimeric genes was studied and compared with that of v-src and v-abl. The v-src/v-abl recombinant shared with v-src and v-abl the ability to transform fibroblasts. In addition, like v-abl, it transformed lymphoid cells and relieved a hematopoietic cell line of its interleukin 3 requirement. In contrast, the reciprocal construct, v-abl/v-src, was transformation defective. Lack of biological activity correlated with formation of a stable complex between the chimeric protein and two cellular proteins and with low kinase activity. We conclude that the specificity within the kinase domain determines the particular biological behavior of protein-tyrosine kinase oncogenes.
Insights
Structural differences within the kinase domain of oncogenes determine their biological activity. Recombining v-abl and v-src oncogenes revealed that specific domains dictate cellular transformation and growth factor independence.
Area of Science:
- Molecular Biology
- Oncology
- Biochemistry
Background:
- v-abl and v-src are oncogenes encoding protein-tyrosine kinases with distinct biological functions.
- Despite high amino acid conservation, their functional differences are not fully understood.
Purpose of the Study:
- To investigate the correlation between structural domains and functional differences of v-abl and v-src oncogenes.
- To identify the specific regions within the kinase domain responsible for their unique biological activities.
Main Methods:
- Construction of chimeric oncogenes by recombining v-abl and v-src downstream of the ATP-binding site lysines.
- Assessment of the biological activity of chimeric and parental oncogenes in cellular transformation assays.
- Analysis of protein complex formation and kinase activity of the resulting chimeric proteins.
Main Results:
- The v-src/v-abl recombinant exhibited biological activity similar to both parental oncogenes, transforming fibroblasts and lymphoid cells.
- This recombinant also relieved a hematopoietic cell line's interleukin 3 dependency, a characteristic of v-abl.
- The reciprocal v-abl/v-src construct was transformation defective, associated with stable protein complex formation and reduced kinase activity.
Conclusions:
- Specificity within the kinase domain is crucial for determining the distinct biological behaviors of protein-tyrosine kinase oncogenes.
- Structural elements within the kinase domain dictate oncogenic potential and cellular dependence on growth factors.