Abstract
Neurotrophins play very important roles in the development and maintenance of the vertebrate nervous system. In mammals, there are four members of the family: NGF, BDNF, NT-3 and NT-4/5. Members of the neurotrophin family activate different receptors that belong to a class of receptor tyrosine kinases known as "Trks." For example, NGF is the specific ligand of TrkA, while BDNF activates TrkB. To elucidate which regions of the two neurotrophins determine the receptor specificities, chimeric neurotrophins were constructed using BDNF as the backbone, with various regions being substituted by the corresponding regions of NGF. The activity of the chimeras on the Trk receptors was assayed in transfected fibroblasts ectopically expressing the Trk receptors. Our findings revealed that, although BDNF is absolutely conserved in mammals, substitution of several small variable regions from NGF into the BDNF backbone did not lead to significant loss in TrkB activity or gain in TrkA activity. Moreover, important determinants of TrkB activation might be located in the carboxy-terminal half of BDNF. On the other hand, critical elements for TrkA activation might be located within the amino-terminal half of the mature NGF molecule.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3 Cells
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Amino Acid Sequence
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Animals
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Binding Sites
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Brain-Derived Neurotrophic Factor / chemistry
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Brain-Derived Neurotrophic Factor / genetics
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Brain-Derived Neurotrophic Factor / metabolism*
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COS Cells
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Cell Survival
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DNA, Complementary / genetics
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Humans
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Mice
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Molecular Sequence Data
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Nerve Growth Factors / chemistry
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Nerve Growth Factors / genetics
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Nerve Growth Factors / metabolism*
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Phosphorylation
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Protein Binding
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Protein Processing, Post-Translational
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Protein Structure, Tertiary
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism*
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Receptor Protein-Tyrosine Kinases / genetics
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Receptor Protein-Tyrosine Kinases / metabolism*
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Receptor, Ciliary Neurotrophic Factor
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Receptor, trkA
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Receptors, Nerve Growth Factor / genetics
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Receptors, Nerve Growth Factor / metabolism*
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / metabolism*
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Sequence Alignment
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Structure-Activity Relationship
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Transfection
Substances
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Brain-Derived Neurotrophic Factor
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DNA, Complementary
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Membrane Proteins
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Nerve Growth Factors
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Proto-Oncogene Proteins
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Receptor, Ciliary Neurotrophic Factor
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Receptors, Nerve Growth Factor
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Recombinant Fusion Proteins
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Receptor Protein-Tyrosine Kinases
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Receptor, trkA