Leukemia inhibitory factor receptor alpha (LIF Rα), also known as CD118, is a subunit of the receptor for leukemia inhibitory factor LIF, which is a pleiotropic cytokine affecting the differentiation, survival and proliferation of a wide variety of cells in the adult and the embryo (1). LIF action is mediated through a high-affinity heterodimeric receptor complex consisting of two membrane glycoproteins: LIF Rα that binds LIF with low affinity and the gp130 subunit that does not bind LIF by itself, but is required for high-affinity binding of LIF by the complex. The gp130 subunit was first described as the signal transducing subunit of the high-affinity IL-6 receptor complex (2). Signaling for the LIF complex is achieved through activation of the JAK-STAT pathway. The LIF complex also mediates the activities of oncostatin M (OSM) (3), cardiotropin-1 and ciliary neurotrophic factor (CNTF) (4). Soluble LIF Rα has been shown to bind LIF and has LIF antagonistic activities. Defects in LIF Rα are the cause of Stueve-Wiedemann syndrome (SWS), a severe autosomal recessive condition and belongs to the group of the bent-bone dysplasias (5).
The predicted molecular weight of Recombinant Human LIF Rα is Mr 89 kDa. However, the actual molecular weight as observed by migration on SDS-PAGE is Mr 100-110 kDa.
Predicted Molecular Mass
89
Formulation
This recombinant protein was 0.2 µm filtered and lyophilized from modified Dulbecco’s phosphate buffered saline (1X PBS) pH 7.2 – 7.3 with no calcium, magnesium, or preservatives.
Storage and Stability
This lyophilized protein is stable for six to twelve months when stored desiccated at -20°C to -70°C. After aseptic reconstitution, this protein may be stored at 2°C to 8°C for one month or at -20°C to -70°C in a manual defrost freezer. Avoid Repeated Freeze Thaw Cycles. See Product Insert for exact lot specific storage instructions.
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Recombinant Human LIF Rα (Leukemia Inhibitory Factor Receptor alpha) is used in research applications to study cytokine signaling, stem cell biology, and cellular differentiation, particularly in contexts where precise control of LIF-mediated pathways is required.
Key reasons to use recombinant human LIF Rα in your research include:
Modeling LIF Signaling: LIF Rα is the high-affinity receptor for LIF, a cytokine critical for maintaining pluripotency in embryonic stem cells and regulating differentiation, hematopoiesis, and inflammation. Recombinant LIF Rα allows for controlled studies of LIF-dependent signaling mechanisms, including activation of the JAK/STAT pathway and downstream gene expression.
Stem Cell Applications: LIF, via its receptor LIF Rα, is essential for maintaining mouse embryonic stem cells in an undifferentiated state and is increasingly studied for its role in human stem cell self-renewal and pluripotency. Recombinant LIF Rα can be used to dissect receptor-ligand interactions, optimize culture conditions, and investigate mechanisms of stem cell maintenance.
Cellular Differentiation and Disease Modeling: LIF Rα is involved in neuronal differentiation, hematopoietic lineage commitment, and inflammatory responses. Recombinant receptor proteins enable functional assays, receptor binding studies, and the development of disease models, such as leukemia or neurodegenerative conditions.
Receptor-Ligand Interaction Studies: Recombinant LIF Rα is valuable for biochemical assays, such as surface plasmon resonance or ELISA, to quantify LIF binding, receptor activation, and downstream signaling events. This is critical for drug screening, antibody development, and mechanistic studies of cytokine-receptor interactions.
High Purity and Consistency: Recombinant proteins offer batch-to-batch consistency, defined purity, and reduced risk of contamination compared to native proteins, which is essential for reproducible experimental results and translational research.
Clinical and Translational Research: Understanding LIF/LIF Rα signaling is relevant for regenerative medicine, fertility treatments, and cancer research, as these pathways influence cell fate decisions, tissue repair, and immune modulation.
In summary, recombinant human LIF Rα is a critical tool for investigating LIF-dependent biological processes, optimizing stem cell culture systems, and developing therapeutic strategies targeting cytokine signaling pathways.
Recombinant Human LIF Rα is generally not suitable as a standard for quantification or calibration in ELISA assays designed to measure LIF protein concentrations. ELISA standards must match the analyte being quantified—in this case, human LIF, not its receptor LIF Rα.
Key points:
ELISA standards should be the same molecule as the target analyte. For quantifying human LIF, the standard must be recombinant human LIF, not LIF Rα.
Recombinant human LIF Rα is a receptor protein, not the cytokine LIF. Using LIF Rα as a standard would not generate an accurate calibration curve for LIF quantification, as the antibodies in LIF ELISA kits are specific for LIF and do not recognize LIF Rα.
Interference risk: Recombinant human LIF Rα can interfere with LIF ELISA assays at concentrations above 25 ng/mL, potentially affecting assay accuracy if present in samples.
Best practice: Use a highly purified recombinant human LIF protein as your standard for LIF quantification in ELISA. This ensures specificity and accuracy of your calibration curve.
Summary Table:
Standard Type
Suitable for LIF ELISA Quantification?
Notes
Recombinant Human LIF
Yes
Matches analyte; recommended for calibration
Recombinant Human LIF Rα
No
Different protein; may interfere at high concentrations
Recommendation: Use recombinant human LIF (not LIF Rα) as your standard for ELISA quantification of LIF. Always match your standard to the analyte detected by your assay antibodies for reliable results.
Recombinant Human LIF Rα (Leukemia Inhibitory Factor Receptor alpha) has been validated in published research primarily for applications involving stem cell maintenance, cell differentiation assays, and functional studies of LIF signaling.
Key validated applications include:
Maintenance of pluripotency in embryonic stem cells: Recombinant human LIF is widely used to support the proliferation and maintenance of mouse embryonic stem cells (mESCs) in an undifferentiated state, as demonstrated by the retention of pluripotency markers such as Oct4, Nanog, and SSEA-1. This application is central to stem cell biology, where LIF/LIFRα signaling is essential for sustaining the naïve state of mESCs.
Cell differentiation assays: The biological activity of recombinant LIF has been validated using the M1 myeloid leukemia cell line, where it induces differentiation into macrophage-like cells. This assay is a standard method for confirming LIF bioactivity and, by extension, the functional engagement of LIFRα. The EC50 and specific activity are often determined using this system.
Functional studies of LIF signaling: Recombinant LIF and its receptor have been used to dissect downstream signaling pathways, including STAT3 activation, in various cell types. These studies help elucidate the pleiotropic effects of LIF/LIFRα in processes such as cell survival, proliferation, and lineage-specific differentiation.
In vivo tumor suppression models: Recombinant human LIF has been tested for its ability to suppress tumor growth in xenograft models, such as medullary thyroid carcinoma (MTC) in mice, implicating LIFRα in mediating these effects.
Comparative bioactivity and glycosylation studies: Recombinant LIF produced in different systems (e.g., rice, E. coli, mammalian cells) has been compared for its ability to activate LIFRα and support stem cell culture, with validation by Western blot, qRT-PCR, and functional assays.
Summary of validated research applications:
Stem cell culture and pluripotency maintenance
Cell differentiation (M1 myeloid cell assay)
Signal transduction and pathway analysis
In vivo tumor suppression studies
Comparative protein bioactivity and glycosylation analysis
These applications are supported by multiple peer-reviewed studies and are considered standard for validating recombinant human LIF and its receptor in both basic and translational research.
To reconstitute and prepare Recombinant Human LIF Rα protein for cell culture experiments, follow these general steps, adapting as needed based on your product’s Certificate of Analysis (CoA):
Equilibrate Materials Allow the lyophilized protein vial and your reconstitution buffer to reach room temperature before opening.
Centrifuge the Vial Briefly centrifuge the vial to collect all lyophilized powder at the bottom.
Select Reconstitution Buffer
If not otherwise specified, use sterile 1× PBS (pH 7.4) or sterile distilled water.
For enhanced stability, especially at low concentrations, add 0.1% endotoxin-free recombinant human serum albumin (HSA) or 0.1% BSA as a carrier protein.
If your application is serum-free or in vivo, avoid animal-derived carriers and consider using trehalose.
Reconstitute to Recommended Concentration
Typical reconstitution concentrations are 0.1–1.0 mg/mL.
For example, to achieve 0.2 mg/mL, add 500 μL buffer to 100 μg protein.
Gently swirl or tap the vial to mix. Avoid vigorous shaking to prevent foaming and denaturation.
Incubate Let the vial stand at room temperature for 15–30 minutes with gentle agitation to ensure complete dissolution.
Aliquot and Storage
Aliquot the reconstituted protein into small volumes (≥20 μL) to avoid repeated freeze-thaw cycles.
For short-term storage (up to 1 week), keep at 2–8 °C.
For long-term storage, freeze aliquots at −20 °C to −80 °C.
If storing at low concentrations, always include a carrier protein to prevent adsorption and degradation.
Preparation for Cell Culture
Thaw aliquots on ice before use.
Dilute the reconstituted stock to the desired working concentration in your cell culture medium immediately before use.
Avoid repeated freeze-thaw cycles to maintain protein integrity.
Additional Notes:
Always consult the product-specific CoA for precise buffer and concentration recommendations, as requirements may vary by manufacturer and formulation.
If the protein does not fully dissolve, allow additional time at room temperature or gentle mixing at 4 °C overnight.
For serum-free or animal-free applications, use only recombinant or synthetic stabilizers.
Summary Table: Key Steps for Recombinant Human LIF Rα Reconstitution
Step
Details
Buffer
Sterile 1× PBS (pH 7.4) ± 0.1% HSA/BSA, or as specified in CoA
Concentration
0.1–1.0 mg/mL (typical); check CoA
Mixing
Gentle swirling/tapping; avoid vigorous shaking
Incubation
15–30 min at room temp, gentle agitation
Aliquoting
≥20 μL aliquots, avoid repeated freeze-thaw
Storage (short-term)
2–8 °C (up to 1 week)
Storage (long-term)
−20 °C to −80 °C (up to 6–12 months)
Carrier protein
0.1% HSA/BSA for stability, unless animal-free required
Always refer to your specific product’s documentation for any unique requirements.
References & Citations
1. Meng, L. et al.(1995) Nature378:724–727 2. Hilton, DJ. et al.(1988) J. of Biol. Chem.263: 9238
Products are for research use only. Not for use in diagnostic or therapeutic procedures.
