Abstract
In vertebrates, commissural axons pioneer a circumferential pathway to the floor plate at the ventral midline of the embryonic spinal cord. Floor plate cells secrete a diffusible factor that promotes the outgrowth of commissural axons in vitro. We have purified from embryonic chick brain two proteins, netrin-1 and netrin-2, that each possess commissural axon outgrowth-promoting activity, and we have also identified a distinct activity that potentiates their effects. Cloning of cDNAs encoding the two netrins shows that they are homologous to UNC-6, a laminin-related protein required for the circumferential migration of cells and axons in C. elegans. This homology suggests that growth cones in the vertebrate spinal cord and the nematode are responsive to similar molecular cues.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Axons / drug effects
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Axons / physiology*
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Base Sequence
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Brain Chemistry*
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Caenorhabditis elegans Proteins*
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Chick Embryo
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Cloning, Molecular
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Dose-Response Relationship, Drug
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Drug Synergism
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Helminth Proteins / genetics
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Molecular Sequence Data
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Nerve Growth Factors / chemistry
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Nerve Growth Factors / isolation & purification
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Nerve Growth Factors / pharmacology
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Nerve Growth Factors / physiology*
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Nerve Tissue Proteins / isolation & purification
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Netrin-1
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Netrins
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Peptide Fragments / chemistry
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Recombinant Proteins / pharmacology
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Sequence Analysis
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Sequence Homology, Amino Acid
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Spinal Cord / cytology
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Spinal Cord / drug effects
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Spinal Cord / growth & development*
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Tumor Suppressor Proteins
Substances
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Caenorhabditis elegans Proteins
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Helminth Proteins
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Nerve Growth Factors
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Nerve Tissue Proteins
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Netrins
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Peptide Fragments
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Recombinant Proteins
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Tumor Suppressor Proteins
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UNC-6 protein, C elegans
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Netrin-1
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netrin-2
Associated data
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GENBANK/L34549
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GENBANK/L34550