Analysis of the human TrkB gene genomic organization reveals novel TrkB isoforms, unusual gene length, and splicing mechanism.
We determined the gene structure of the human TrkB gene. The gene is unusually large and spans at least 590 kbp. It contains 24 exons. Using alternative promoters, splicing, and polyadenylation sites, the gene can create at least 100 isoforms, that can encode 10 proteins. RT-PCR and Northern blot analysis reveals that only three major protein isoforms are generated by the gene: the full length receptor, an isoform lacking the tyrosine kinase domain, and a novel isoform lacking the tyrosine kinase domain but containing a Shc binding site. This novel isoform, TrkB-T-Shc is generated by the use of a new alternative exon 19. It is expressed only in brain. TrkB-T-Shc protein is located in the plasma membrane. Coimmunoprecipitation experiments show that TrkB-T-Shc is not phosphorylated by the full length receptor, indicating that it could be a negative regulator of TrkB signaling in the brain.
Stoilov
Peter
P
Friedrich-Alexander-University Erlangen, Institute for Biochemistry, Fahrstrasse 17, Erlangen, 91054, Germany.
Castren
Eero
E
Stamm
Stefan
S
D020121:5' Untranslated Regions; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D020134:Catalytic Domain; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005796:Genes; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D026723:Polyadenylation; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000737:chemistry; D022821:RNA Splice Sites; D012333:RNA, Messenger / Q000378:metabolism; D020813:Receptor, trkB / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D020033:Protein Isoforms; D011506:Proteins; D022821:RNA Splice Sites; D012333:RNA, Messenger; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D020813:Receptor, trkB