Expression of a novel form of the fyn proto-oncogene in hematopoietic cells

New Biol. 1989 Oct;1(1):66-74.


The fyn proto-oncogene encodes a 59-kD membrane-associated protein-tyrosine kinase that is implicated in the control of cell growth. We report here that there are two distinct fyn-encoded transcripts that exhibit mutually exclusive expression patterns; one form is found in thymocytes, splenocytes, and some hematolymphoid cell lines, while a second form accumulates principally in brain. The thymocyte and brain forms of p59fyn differ in their kinase domains, and are generated by mutually exclusive alternative splicing of a single exon. Immunoprecipitation followed by in vitro autophosphorylation demonstrates that both forms of p59fyn are enzymatically active. Our results define a novel form of the p59fyn protein-tyrosine kinase, with an altered catalytic domain, that apparently participates in a specialized signal transduction pathway in hematopoietic cells.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Brain / enzymology*
  • Cell Line
  • Enzyme Induction
  • Exons
  • Genes, src
  • Humans
  • Isoenzymes / genetics*
  • Isoenzymes / physiology
  • Lymphoid Tissue / chemistry
  • Lymphoid Tissue / cytology
  • Mice
  • Molecular Sequence Data
  • Multigene Family
  • Phosphorylation
  • Protein-Tyrosine Kinases / genetics*
  • Protein-Tyrosine Kinases / physiology
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins / physiology
  • Proto-Oncogene Proteins c-fyn
  • RNA Splicing*
  • Sequence Homology, Nucleic Acid
  • Species Specificity
  • T-Lymphocytes / enzymology*


  • Isoenzymes
  • MAS1 protein, human
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins
  • Protein-Tyrosine Kinases
  • FYN protein, human
  • Fyn protein, mouse
  • Proto-Oncogene Proteins c-fyn