Recombinant Human Platelet Factor 4 (PF4) protein is expressed in E. coli and represents the full length of the mature protein, spanning amino acids 32 to 101. This tag-free protein is highly pure, with a purity greater than 97% as verified by SDS-PAGE. It appears to be fully biologically active, with activity confirmed through a chemotaxis bioassay using human fibroblasts at concentrations of 1.0-10 ng/ml. The endotoxin level is maintained at less than 1.0 EU/µg, determined by the LAL method.
Platelet Factor 4 (PF4) belongs to the CXC chemokine family and seems to play a significant role in modulating immune and inflammatory responses. Activated platelets release it primarily from alpha granules, and it's involved in processes such as chemotaxis, where it influences the migration of various immune cells. Researchers also study PF4 for its involvement in coagulation and its potential impact on angiogenesis, making it a protein of interest across multiple research fields.
Potential Applications
Note: The applications listed below are based on what we know about this protein's biological functions, published research, and experience from experts in the field. However, we haven't fully tested all of these applications ourselves yet. We'd recommend running some preliminary tests first to make sure they work for your specific research goals.
1. Chemotaxis Assay Development and Optimization
This recombinant PF4 protein may serve as a positive control and reference standard in chemotaxis assays using various cell types, particularly fibroblasts as demonstrated in the activity testing. The defined concentration range of 1.0-10 ng/ml for biological activity gives researchers precise dosing parameters for experimental design. High purity (>97%) and low endotoxin levels make it suitable for cell-based assays where contamination could confound results. Researchers might find this protein valuable for validating new chemotaxis assay protocols or comparing chemotactic responses of different cell populations.
2. Antibody Development and Validation
The tag-free nature and high purity of this recombinant PF4 protein likely make it an excellent immunogen for generating specific antibodies against human PF4. The protein can be used to immunize laboratory animals for polyclonal antibody production or as an antigen for monoclonal antibody screening. It also serves as a positive control in antibody validation experiments, including ELISA, Western blotting, and immunofluorescence assays. The biological activity confirmation suggests that the recombinant protein maintains native-like conformational epitopes important for antibody recognition.
3. Protein-Protein Interaction Studies
This biologically active PF4 protein can be used in biochemical assays to investigate its interactions with known binding partners, such as heparin, glycosaminoglycans, or cell surface receptors. Pull-down assays, surface plasmon resonance, or co-immunoprecipitation experiments may be performed to characterize binding kinetics and affinities. The maintained biological activity suggests proper protein folding, which appears crucial for authentic interaction studies. These investigations could provide insights into PF4's molecular mechanisms and potentially identify new binding partners.
4. Cell Migration and Wound Healing Research
Given the demonstrated chemotactic activity on human fibroblasts, this PF4 protein can be used in in vitro wound healing and cell migration studies. Researchers might find it useful in scratch assays, transwell migration chambers, or time-lapse microscopy experiments to study cellular responses to PF4 stimulation. The defined active concentration range allows for dose-response studies to determine optimal conditions for various experimental setups. This application may be particularly relevant for understanding tissue repair mechanisms and cellular responses to platelet-derived factors.
5. Comparative Functional Analysis
This recombinant protein likely serves as a reference standard for comparing the biological activity of PF4 variants, mutants, or proteins from different expression systems. Researchers can use it alongside modified versions of PF4 to assess how structural changes affect chemotactic activity. The established activity testing method using human fibroblasts provides a standardized assay format for such comparative studies. This application appears valuable for protein engineering research and understanding structure-function relationships in the PF4 protein family.
