Product Specifications for Recombinant Human Follistatin-like 1 Protein, CF
Mouse myeloma cell line, NS0-derived human Follistatin-like 1/FSTL1 protein Met1-Ile308, with a C-terminal Asp and 10-His tag
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
<0.10 EU per 1 μg of the protein by the LAL method.
N-terminal sequence Analysis
Predicted Molecular Mass
45-50 kDa, reducing conditions
Measured by its binding ability in a functional ELISA. When Recombinant Human Follistatin‑like 1/FSTL1 is coated at 2 μg/mL (100 μL/well), the concentration of recombinant human BMP-4 that produces 50% of the optimal binding response is found to be approximately 10-60 ng/mL.
Formulation, Preparation and Storage
What does CF mean?
CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our
Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant
protein to be stored at a more dilute concentration.
The carrier free version does not contain BSA.
What formulation is right for me?
In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or
as an ELISA standard.
In contrast, the carrier free protein is recommended for applications, in which the presence of BSA
Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitute at 200 μg/mL in PBS.
The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage:
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
12 months from date of receipt, -20 to -70 °C as supplied.
1 month, 2 to 8 °C under sterile conditions after reconstitution.
3 months, -20 to -70 °C under sterile conditions after reconstitution.
Background: Follistatin-like 1/FSTL1
Follistatin‑like 1 (FSL1 or FSTL1), also known as FRP (follistatin‑related protein), Flik (follistatin‑like), and TSC‑36 (TGF‑ beta 1‑stimulated clone 36), is a secreted 45‑55 kDa extracellular glycoprotein belonging to the BM‑40/SPARC/Osteonectin family (1‑3). The human FSL‑1 cDNA encodes 308 amino acids (aa), including a 20 aa signal sequence, a cysteine‑rich Follistatin (EGF- and kazal‑like) domain, two apparently non‑functional EF‑hand calcium‑binding motifs, and a von Willebrand Factor C homology domain (1, 3). Mature human FSL1 shares 94%, 95%, 98% and 99% aa identity with mouse, rat, bovine and equine FSL1, respectively. FSL1 was first identified as a TGF‑ beta ‑induced protein from a mouse osteoblast cell line (4). It is ubiquitously expressed in early mouse development, but is mainly mesenchymal later in development (5). In vitro, FSTL1 interacts directly with BMP‑4, while in vivo, it regulates BMP‑4 signaling during normal lung development, as demonstrated by lethal respiratory failure in mice deleted for FSTL1 (6). In humans, FSL1 is a common rheumatoid arthritis auto‑antigen (2). It is reported to be either pro‑inflammatory due to promoting inflammatory cytokine secretion, or to prevent autoimmune arthritis by inhibiting matrix metalloproteinase (MMP) and prostaglandin expression (7‑10). In muscle and heart, it appears to be protective and promotes endothelial cell functions such as revascularization after ischemia, probably due to promoting expression and activation of the protein kinase AKT1 (11, 12). Cardiac and circulating FSL1 is generally increased in conditions such as heart failure and acute coronary syndrome (12‑14). FSL1 also appears to be a tumor suppressor, showing down‑regulated expression in many human cancers (4, 15, 16). In vitro, it slows proliferation and MMP‑dependent migration, and increases FAS‑dependent apoptosis of tumor cell lines (15).
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Entrez Gene IDs
11167 (Human); 14314 (Mouse); 79210 (Rat)
FLJ50214, FRP, FRPFLJ52277, FSL1, FSTL1, Flik, Follistatin-like 1, Follistatin-like protein 1, Follistatin-related Protein, TSC-36, follistatin-related protein 1
Which Brands are Currently Available on bio‑techne.com? R&D Systems, Tocris Bioscience and ProteinSimple branded products are available to purchase through bio‑techne.com. ProteinSimple branded instruments are available to quote. ACD branded products will be available on bio‑techne.com in the near future. Novus Biologicals branded products are not currently available on bio‑techne.com and can be found at novusbio.com.
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