Human flt3-ligand, rec.

Recombinant human Flt3-Ligand produced in E.Coli is a non-glycosylated, polypeptide chain of 155 amino acids and a molecular mass of approximately 17.6kDa.

Flt3 ligand (FL) is a hematopoietic four helical bundle cytokine. It is structurally homologous to stem cell factor (SCF) and colony stimulating factor 1 (CSF-1). In synergy with other growth factors, Flt3 ligand stimulates the proliferation and differentiation of various blood cell progenitors.

Amino acid sequence:
TQDCSFQHSP ISSDFAVKIR ELSDYLLQDY PVTVASNLQD EELCGGLWRL VLAQRWMERL KTVAGSKMQG LLERVNTEIH FVTKCAFQPP PSCLRFVQTN ISRLLQETSE QLVALKPWIT RQNFSRCLEL QCQPDSSTLP PPWSPRPLEA TAPTA.

Biological Activity:
The ED50 as calculated by the dose-dependent stimulation of the proliferation of human AML5 cells is less than 1.0ng/mL, corresponding to a Specific Activity of 1.0×10E6 IU/mg.

The natural Flt-3 ligand (FL/Flt-3L) has been found to be a type I transmembrane glycoprotein of approximately 30 kDa. Although it is known to exist naturally as a non-disulfide-linked homodimer, multiple forms of the ligand are known, including a soluble form. Generally, the extracellular portion is approximately 160 aa residues in length and the cytoplasmic segment is approximately 20-30 aa residues in length. Mouse and human FL are about 70% identical at the amino acid level, and both show cross-species reactivity. The Kd for FL binding to Flt-3 is reported to be approximately 0.7nM. In their extracellular domains, Flt-3 ligand, stem cell factor (SCF), and FMS-ligand (M-CSF) show a four-helix bundle structure and demonstrate four conserved cysteines. Cells known to express FL include human and mouse T cell lines a thymic stromal cell line, and bone marrow fibroblasts.