title: Five Trk receptors in the zebrafish.
abstract: Using a homology-based cloning strategy we have identified five members of the Trk family in the zebrafish Danio rerio. They are homologous to the three mammalian Trk receptors in their conserved intracellular kinase regions and the organization of their extracellular regions. The five trk genes are differentially expressed in the developing brain, spinal cord, cranial ganglia, and retina. Full-length forms of three of the trk genes are expressed when neurons pioneer the major axon tracts, whereas the two other trk genes have a later onset of expression. Truncated transcripts and forms containing an extracellular juxtamembrane region insert were found. The degree of sequence variation and expression differences within the family suggest that each of the five zebrafish Trk receptors have a functionally distinct role. These findings demonstrate that the vertebrate Trk family is larger than previously appreciated.
authors.affiliation: Section of Biomolecular Medicine, Boston University Medical Center, Massachusetts 02118, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Martin
authors.forename: G
authors.initials: G
authors.lastname: Marazzi
authors.forename: J H
authors.initials: JH
authors.lastname: Sandell
authors.forename: G
authors.initials: G
authors.lastname: Heinrich
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D001921:Brain / Q000196:embryology / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005306:Fertilization; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor / Q000737:chemistry / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor