Flt-3 ligand (FL) is a recently identified hematopoietic cytokine whose activities are mediated by binding to the transmembrane glycoprotein Flt-3. Flt-3 was first discovered as a member of the class III subfamily of receptor tyrosine kinases (RTK) whose expression among hematopoietic cells was found to be restricted to highly enriched stem/progenitor cell populations. Additionally, class III RTKs include the receptors from SCF, M-CSF and PDGF. Not surprisingly, Flt-3 ligand is also structurally related to M-CSF and SCF. All three cytokines have been shown to exist both as type I transmembrane proteins and as soluble proteins. The predominant human FL isoform is a transmembrane protein that can undergo proteolytic cleavage to generate a soluble form of the protein. FL has been shown to synergize with a wide variety of hematopoietic cytokines to stimulate the growth and differentiation of early hematopoietic progenitors.
Reference
1. Hacein-Bey S, Basile GD, Lemerle J, et al. 1998. Blood, 92: 4090-7
2. Peters M, Solem F, Goldschmidt J, et al. 2001. Exp Hematol, 29: 146-55
3. Beq S, Fontanet A, Theze J, et al. 2004. AIDS, 18: 2089-91
4. Mahadevan D, Choi J, Cooke L, et al. 2009. Hum Genomics Proteomics, 2009: 453634
5. Coates PT, Barratt-Boyes SM, Zhang L, et al. 2003. Blood, 102: 2513-2
1.