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Identification of a developmentally regulated protein-tyrosine kinase by using anti-phosphotyrosine antibodies to
1Department of Biology, University of California, San Diego, La Jolla 92093.
Abstract:
To identify the protein-tyrosine kinases that are expressed during chicken embryonic development, a 10-day chicken embryo cDNA expression library was screened with anti-phosphotyrosine antibodies. Of the positive clones isolated, many encoded the same protein-tyrosine kinase, which we designate Cek1 (chicken embryo kinase 1). Its amino acid sequence suggests that the Cek1 protein is a transmembrane tyrosine kinase and presumably the receptor for an unknown ligand. Antibodies prepared to the cloned Cek1 kinase recognize, in immunoblotting experiments, two protein bands with apparent molecular weights of 100,000 and 110,000. The Cek1 protein was detected in many chicken embryonic tissues, but not in the corresponding adult tissues (with the exception of brain). The Cek1 kinase appears to be very closely related to two protein-tyrosine kinases whose partial sequences have been recently determined, human Flg and mouse Bek. Cloning using anti-phosphotyrosine antibodies has allowed us to detect, in addition to Cek1, several other protein-tyrosine kinases that are expressed during chicken embryonic development, some of which have not been previously identified.
Insights
Researchers identified Cek1 (chicken embryo kinase 1), a novel transmembrane tyrosine kinase, during chicken embryonic development. This protein is crucial for embryonic tissues but less so in adults, suggesting a key developmental role.
Area of Science:
- Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Protein-tyrosine kinases play critical roles in cellular signaling pathways.
- Understanding the expression of these kinases during embryonic development is essential for deciphering developmental processes.
Purpose of the Study:
- To identify novel protein-tyrosine kinases expressed during chicken embryonic development.
- To characterize a newly identified kinase, Cek1 (chicken embryo kinase 1).
Main Methods:
- Screening of a 10-day chicken embryo cDNA expression library using anti-phosphotyrosine antibodies.
- Amino acid sequencing to predict protein structure and function.
- Antibody-based immunoblotting to detect protein expression and molecular weight.
- Tissue expression analysis in embryonic and adult chicken tissues.
Main Results:
- Identification and cloning of Cek1, a novel transmembrane tyrosine kinase.
- Cek1 protein detected in multiple embryonic chicken tissues, with limited expression in adult tissues (except brain).
- Cek1 shows high sequence similarity to human Flg and mouse Bek kinases.
- Several other previously unidentified protein-tyrosine kinases were also detected.
Conclusions:
- Cek1 is a significant protein-tyrosine kinase involved in chicken embryonic development.
- The expression pattern suggests a role for Cek1 in developmental processes rather than adult tissue maintenance.
- The discovery of Cek1 and other kinases provides new insights into the molecular mechanisms of embryonic development.