Macrophage Colony-Stimulating Factor 1 (M-CSF), involved especially in monocytopoiesis,[1]is a hematopoietic growth factor. In mammals, it exits three isoforms, which invariably share an N-terminal 32-aa signal peptide, a 149-residue growth factor domain, a 21-residue transmembrane region and a 37-aa cytoplasmictail[2]. The biological activity of human M-CSF is maintained within the 149-aa growth factor domain[3], and it is only active in the disulfide-linked dimeric form[4], which is bonded at Cys63.
Recombinant human Macrophage Colony-Stimulating Factor 1 (rhM-CSF) produced in E. coli is a disulfide-linked homodimer containing two non-glycosylated polypeptide chains of 159 amino acids each. A fully biologically active molecule, rhM-CSF has a molecular mass of 28 kDaanalyzed by non-reducing SDS-PAGE and is obtained by proprietary refolding and chromatographic techniques at GenScript.