title: TrkB variants with deletions in the leucine-rich motifs of the extracellular domain.
abstract: We have isolated two novel variants involving the extracellular domain of TrkB from developing sensory neurons. These variants are generated by alternative splicing and lack two or all three of the leucine-rich motifs. Each of these variants is expressed as isoforms that possess or lack the intracellular tyrosine kinase domain. Fibroblast cell lines stably expressing these variants do not bind any of the TrkB ligands (brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4/5) and neither survive nor undergo morphological transformation in response to neurotrophins. These results demonstrate that the leucine-rich motifs in TrkB are essential for ligand binding and signaling and indicate that the extracellular immunoglobulin-like domains alone are insufficient to confer neurotrophin binding to TrkB.
authors.affiliation: School of Biological and Medical Sciences, University of St. Andrews, St. Andrews, Fife KY16 9AJ, Scotland.
authors.forename: N
authors.initials: N
authors.lastname: Ninkina
authors.forename: M
authors.initials: M
authors.lastname: Grashchuck
authors.forename: V L
authors.initials: VL
authors.lastname: Buchman
authors.forename: A M
authors.initials: AM
authors.lastname: Davies
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D017353:Gene Deletion; D005786:Gene Expression Regulation; D007930:Leucine / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000378:metabolism; D020801:Receptor, Ciliary Neurotrophic Factor; D017475:Receptors, Nerve Growth Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D009414:Nerve Growth Factors; D020801:Receptor, Ciliary Neurotrophic Factor; D017475:Receptors, Nerve Growth Factor; D007930:Leucine