Flt-3 Ligand/FLT3L, Human, HEK293 Cells,Tag Free

Flt-3 Ligand (FLT3L) iis an alpha-helical cytokine that promotes the differentiation of multiple hematopoietic cell lineages (1-3). Mature human Flt-3 Ligand consists of a 158 amino acid (aa) extracellular domain (ECD) with a cytokine-like domain and a juxtamembrane tether region, a 21 aa

transmembrane segment, and a 30 aa cytoplasmic tail (4-7). Within the ECD, human Flt-3 Ligand shares 71% and 65% aa sequence identity with

mouse and rat Flt-3 Ligand, respectively (4-6). The human and mouse Flt-3 Ligand proteins show cross-species activity. Flt-3 Ligand is also

structurally related to M-CSF and SCF. Flt-3 Ligand is widely expressed in various human and mouse tissues. It is expressed as a noncovalently-linkeddimer by T cells and bone marrow and thymic fibroblasts (1, 8). Each 36 kDa chain of the Flt-3 Ligand dimer carries approximately 12 kDa of N- and

O-linked carbohydrates (8). Alternate splicing and proteolytic cleavage of the transmembrane form of the Flt-3 Ligand protein can generate a soluble 30

kDa fragment that includes the cytokine-like domain (4, 8). Alternate splicing of human Flt-3 Ligand also generates membrane-associated isoforms

that contain either a truncated cytoplasmic tail or an 85 aa substitution following the cytokine-like domain in the ECD of the Flt-3 Ligand protein (4, 5, 8).

Both transmembrane and soluble forms of Flt-3 Ligand signal through the tyrosine kinase receptor Flt-3/Flk-2 (3, 4, 6, 7). Flt-3 Ligand induces the

expansion of monocytes and immature dendritic cells as well as early B cell lineage differentiation (2, 9). Additionally, Flt-3 Ligand synergizes with IL-3, GM-CSF, and SCF to promote the mobilization and myeloid differentiation of hematopoietic stem cells (4-6). Flt-3 Ligand also cooperates with IL-2,

IL-6, IL-7, and IL-15 to induce NK cell development and with IL-3, IL-7,and IL-11 to induce terminal B cell maturation (1, 10). 

1. Wodnar-Filipowicz, A. (2003) News Physiol. Sci. 18:247.

2. Dong, J. et al. (2002) Cancer Biol. Ther. 1:486.

3. Gilliland, D.G. and J.D. Griffin (2002) Blood 100:1532.

4. Hannum, C. et al. (1994) Nature 368:643.

5. Lyman, S.D. et al. (1994) Blood 83:2795.

6. Lyman, S.D. et al. (1993) Cell 75:1157.

7. Savvides, S.N. et al. (2000) Nat. Struct. Biol. 7:486.

8. McClanahan, T. et al. (1996) Blood 88:3371.

9. Diener, K.R. et al. (2008) Exp. Hematol. 36:51.

10. Farag, S.S. and M.A. Caligiuri (2006) Blood Rev. 20:123.