|Cat. No. :
|Product Overview :
||Recombinant rat LIF is expressed in E. coli as a fusion protein with GST using the pGEX expression system, cleaved from GST moiety with thrombin and purified by ion-exchange chromatography. Rat LIF (rtLIF) is a 19.9 kDa protein containing 183 amino acid residues that exhibits 91% amino acid sequence identity with murine LIF1.
||Leukemia Inhibitory Factor (LIF) is a lymphoid factor which promotes long-term maintenance of embryonic stem cells by suppressing spontaneous differentiation. LIF has a number of other activities including cholinergic neuron differentiation, control of stem cell pluripotency, bone and fat metabolism, mitogenesis of certain factor dependent cell lines and promotion of megakaryocyte production in vivo. Analysis of the secondary structure of rat and murine LIF indicates a difference in the two dimensional structure of both proteins. Studies have shown that rtLIF is more effective in maintaining the undifferentiated phenotype of rat ES cells than similar concentrations of murine LIF.
||Greater than 85% by analytical HPLC and SDS-PAGE.
||Liquid in 50mM sodium phosphate / 1mM DTT / 10% glycerol / 250mM NaCl, pH 7.4 and 0.02% Tween 20. No preservativies added.
|Endotoxin Levels :
||Endotoxin level is less than 0.1 ng per μg of LIF. Tested negative in both aseptic and mycoplasma tests.
||The activity of rat LIF is determined by the ability to induce differentiation of M1 myeloid leukemic cells. The minimum detectable concentration of rat LIF in this assay is 0.5 ng/mL. The specific activity is >1 x 108 units/mg, where 50 units is defined as the amount of rat LIF required to induce differentiation in 50% of the M1 colonies in 1 mL agar cultures.
||Rat LIF is shipped on dry ice. Maintain at -20°Cuntil expiration date. Further dilutions should be made into buffer or medium to which protein (e.g., 1% BSA) or Tween 20 has been added and stored at -20°C. Freeze thawing is not recommended.