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Characterization and functional allotment of proto-oncogenes belonging to the src family
K Toyoshima1, Y Yamanashi, T Katagiri
1Institute of Medical Science, University of Tokyo, Japan.
Abstract:
Eight proto-oncogenes encode cytoplasmic protein tyrosine kinases whose primary structures are closely related to that of p60proto-src. This group of related genes is called the src-family. Their products share common structures: namely, a glycine residue at position 2 from the N terminus, a unique domain, a modulatory domain (SH2, SH3), a kinase (catalytic) domain, and a regulatory domain. Oncogenic activation of these genes may occur by various mutations such as 1) deletion or substitution of the tyrosine at the C-terminal position, 2) mutation at a defined position in the kinase domain or 3) deletion or mutation in the modulatory domain. The expressions of the proto-oncogenes of this family are tissue specific and are unique for each gene, suggesting functional allotment of these gene products. In the hematopoietic system, the genes appear to be expressed in specific cell lineages. In this paper, the functional allotments of these genes in the hematopoietic system are considered with special reference to the functions of lck, lyn, and fyn in cells of T and B lymphocyte lineages.
Insights
The src-family of protein tyrosine kinases plays crucial roles in cell signaling. This study examines their specific functions within T and B lymphocyte lineages in the hematopoietic system.
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- The src-family comprises eight proto-oncogenes encoding cytoplasmic protein tyrosine kinases.
- These kinases share conserved structural domains, including SH2 and SH3 modulatory domains and a catalytic kinase domain.
- Oncogenic activation can result from mutations in the C-terminal tyrosine, kinase domain, or modulatory domains.
Purpose of the Study:
- To investigate the functional roles of src-family genes within the hematopoietic system.
- To specifically examine the functions of lck, lyn, and fyn in T and B lymphocyte development and function.
Main Methods:
- Comparative analysis of src-family gene structures and known mutations.
- Review of expression patterns within hematopoietic cell lineages.
- Focus on the roles of specific src-family members (lck, lyn, fyn) in lymphocyte biology.
Main Results:
- Src-family gene expression is tissue-specific and unique for each gene, indicating distinct functional roles.
- These genes are expressed in specific hematopoietic cell lineages.
- lck, lyn, and fyn exhibit specialized functions within T and B lymphocyte lineages.
Conclusions:
- The src-family of protein tyrosine kinases is critical for hematopoietic cell function.
- Specific members like lck, lyn, and fyn are essential for T and B lymphocyte lineage development and signaling.
- Understanding these roles is key to comprehending lymphocyte biology and associated diseases.