Ficolin-1 (fibrinogen/collagen-like), also called M-ficolin, is a member of the ficolin family of secreted pattern recognition proteins in the lectin complement activation pathway (1-3). Ficolin-1 is expressed by monocytes, neutrophils and type II alveolar epithelial cells (2-5). It is proposed to be a locally-acting lectin released in a regulated manner (4). Ficolin-1 is not found in plasma, but is detected on the surface of circulating monocytes (4-6). The 35kD, 326 amino acid (aa) human ficolin-1 contains a 28 aa signal sequence, an N-terminal collagen domain and a C-terminal fibrinogen-like (FBG) domain that includes a calcium binding site and one potential N-glycosylation site. Both the collagen and FBG domains mediate trimer formation (7). Like ficolin-2, larger homo-multimers of ficolin-1 exist and are likely formed by disulfide bonds at the N-terminus. Sizes corresponding to 12 or 18 subunit oligomers are reported (4, 6, 7). The FBG domain of Ficolin-1 binds microbial ligands that contain acetylated compounds (6). Ligands identified include N-acetyl glucosamine, N-acetyl galactosamine and sialyl-N-acetyllactosamine (4-7). Like other ficolins, ficolin-1 associates with, and activates the MBL-associated serine protease (MASP) complex, which activates the complement pathway by cleaving C4, contributing to the innate immune response (4-6). The ficolin-1 gene is polymorphic, showing at least ten single nucleotide polymorphisms in the promoter and coding regions (1). Product Description: Mouse myeloma NSO cell line-derived recombinant human Ficolin-1 (Gln28 thru Ala326, NCBI accession O00602) with a C-terminal 10x His tag. Molecular Mass: Predicted: 33.4kD Observed: 35-36kD (reducing conditions) Activity: Measured by its ability to bind immobilized Fetuin in a functional ELISA (Liu, Y. et al. (2005) J. Immunol. 175:3150). Storage and Stability: Lyophilized powder is stable for 12 months at -20C Reconstituted product is stable for 3 months at -20C or lower under sterile conditions. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
