Ligand for FLT3/FLK2 receptor tyrosine kinase regulates growth of haematopoietic stem cells and is encoded by variant RNAs

Nature. 1994 Apr 14;368(6472):643-8. doi: 10.1038/368643a0.


The FLT3/FLK2 receptor tyrosine kinase is closely related to two receptors, c-Kit and c-Fms, which function with their respective ligands, Kit ligand and macrophage colony-stimulating factor to control differentiation of haematopoietic and non-haematopoietic cells. FLT3/FLK2 is thought to be present on haematopoietic stem cells and found in brain, placenta and testis. We have purified to homogeneity and partially sequenced a soluble form of the FLT3/FLK2 ligand produced by mouse thymic stromal cells. We isolated several mouse and human complementary DNAs that encode polypeptides with identical N termini and different C termini. Some variants contain hydrophobic transmembrane segments, suggesting that processing may be required to release soluble ligand. The purified ligand enhances the response of mouse stem cells and a primitive human progenitor cell population to other growth factors such as interleukins IL-3 and IL-6 and to granulocyte-macrophage colony-stimulating factor, and also stimulates fetal thymocytes.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Division / physiology
  • Cell Line
  • Culture Media, Conditioned
  • DNA, Complementary
  • Genetic Variation
  • Hematopoietic Stem Cells / cytology*
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Mice
  • Molecular Sequence Data
  • Proto-Oncogene Proteins / metabolism*
  • RNA, Messenger / genetics
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Sequence Homology, Amino Acid
  • fms-Like Tyrosine Kinase 3


  • Culture Media, Conditioned
  • DNA, Complementary
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • flt3 ligand protein
  • FLT3 protein, human
  • Flt3 protein, mouse
  • Receptor Protein-Tyrosine Kinases
  • fms-Like Tyrosine Kinase 3

Associated data

  • GENBANK/U04806
  • GENBANK/U04807