LIF Human, GST

Human LIF is a glycoprotein with a molecular weight of approximately 19.7 kDa, consisting of 181 amino acid residues . The recombinant form of LIF is often expressed in Escherichia coli (E. coli) as a fusion protein with Glutathione S-transferase (GST) using the pGEX expression system . This fusion protein is then cleaved from the GST moiety with thrombin and purified by High-Performance Liquid Chromatography (HPLC) .

LIF has a wide range of biological activities:

• Stem Cell Maintenance: It promotes the long-term maintenance of embryonic stem cells by suppressing spontaneous differentiation .
• Hematopoietic Differentiation: LIF induces differentiation in normal and myeloid leukemia cells .
• Neuronal Differentiation: It plays a role in the differentiation of neuronal cells .
• Immune Regulation: LIF is a key player in immune tolerance at the maternal-fetal interface .

The activity of human LIF is determined by its ability to induce differentiation of M1 myeloid leukemic cells. The minimum detectable concentration of human LIF in this assay is 0.5 ng/mL, with a specific activity of greater than 1 x 10^8 units/mg . This makes LIF a valuable tool in both research and clinical settings, particularly in the fields of stem cell biology and cancer research.

Recombinant human LIF is typically stored in a liquid form in phosphate-buffered saline (PBS) with a pH of 7.4 and 0.02% Tween 20 . It should be maintained at 2-8°C until its expiration date .

The discovery of LIF dates back to 1969, when it was first described as a factor that could induce differentiation in murine myeloid leukemia cells . Over the years, LIF has been rediscovered and studied in various contexts, leading to a better understanding of its multifunctional roles in different biological systems .