Murine Flt3, a Gene Encoding a Novel Tyrosine Kinase Receptor of the PDGFR/CSF1R Family

Receptor-type tyrosine kinases presenting an extracellular region with five immunoglobulin-like domains, and strongly related by sequence similarities in the intracellular region, constitute a family of receptors involved in development and function of various cell lineages. We have isolated and characterized the mouse Flt3 gene, encoding the sixth member of this family. The Flt3 gene possesses an open reading frame of 3000 nucleotides, and therefore appears to code for a protein of 1000 amino acids. The deduced structure of the FLT3 protein presents all the characteristics of a receptor-type kinase of this family. The gene is expressed in placenta, in various adult tissues including gonads and brain, and in hematopoietic cells. The Flt3 transcript is 3.7 kb long, except in the testis, where two shorter post-meiotic transcripts are detected. These results suggest a role for this novel receptor and its yet unidentified ligand in placenta, gonads and hematopoietic and nervous systems.