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Identification of receptor tyrosine kinases in the embryonic chicken lens
J D Potts1, G J Harocopos, D C Beebe
1Department of Anatomy and Cell Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814.
Abstract:
Protein phosphorylation plays a critical role in the control of growth and regulation of many eukaryotic cells. Members of the protein tyrosine kinase (PTK) family of peptides function as growth factor receptors and oncoproteins. A common feature of members of the PTK family is a highly conserved intracellular catalytic domain. We analyzed the chicken lens epithelium, which responds to several known growth factors, for the presence of receptor PTK's. Using reverse transcription polymerase chain reaction (rtPCR) and degenerate primers made to conserved regions within kinase domains, we amplified RNA from embryonic day 6 (E6) lens epithelium and sequenced 135 cDNA clones. Sixteen distinct kinase sequences were obtained. Eight of these sequences represented kinase domains of known mammalian growth factor receptors, and six represented intercellular kinases. Two sequences appeared to code for new kinases. The amino acid identity of the chicken homologs ranged from 80-100% when compared to their mammalian counterparts.
Insights
Researchers identified 16 distinct protein tyrosine kinase (PTK) sequences in embryonic chicken lens epithelium. This study reveals conserved PTK domains crucial for cell growth and regulation in vertebrates.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- Protein phosphorylation is vital for eukaryotic cell growth and regulation.
- Protein tyrosine kinases (PTKs) are key regulators, acting as growth factor receptors and oncoproteins.
- PTK family members share a conserved intracellular catalytic domain.
Purpose of the Study:
- To investigate the presence of receptor PTKs in the chicken lens epithelium.
- To identify novel kinase sequences within this tissue.
Main Methods:
- Utilized reverse transcription polymerase chain reaction (rtPCR) with degenerate primers.
- Targeted conserved regions within kinase domains of RNA from embryonic day 6 (E6) chicken lens epithelium.
- Sequenced 135 complementary DNA (cDNA) clones.
Main Results:
- Obtained 16 distinct kinase sequences from the chicken lens epithelium.
- Identified eight sequences homologous to known mammalian growth factor receptors.
- Found six sequences corresponding to intercellular kinases.
- Discovered two novel kinase sequences.
Conclusions:
- The chicken lens epithelium expresses a diverse range of PTKs, including homologs of known mammalian receptors.
- The high amino acid identity (80-100%) suggests significant conservation of PTKs across species.
- This finding provides insights into the molecular mechanisms of lens development and growth factor signaling.