Recombinant Rat Prolactin protein (Prl) is expressed in E. coli and spans the full length of the mature protein from amino acids 30 to 226. This tag-free protein appears to be of high purity, exceeding 98% as verified by SDS-PAGE analysis. It exhibits full biological activity, with an ED50 of less than 1.0 ng/ml in a rat Nb2-11 cell proliferation assay, indicating a specific activity greater than 1.0 × 10^6 IU/mg. Endotoxin levels are maintained below 1.0 EU/µg, as measured by the LAL method.
Most researchers know prolactin as the hormone behind lactation and milk production in mammals. What's less obvious is how this protein reaches into many other biological processes - immune system regulation, cell growth, even behaviors that seem unrelated to reproduction. This versatility is likely why prolactin has become such an important research target in endocrinology and physiology, offering windows into cellular pathways that might otherwise remain hidden.
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. Cell Proliferation and Viability Assays
This recombinant rat prolactin is highly biologically active (ED₅₀ < 1.0 ng/ml) and suitable as a positive control in proliferation assays using prolactin-responsive cells like Nb2-11. The high purity and low endotoxin support reliable dose-response studies. However, researchers should validate its activity in primary rat cell systems beyond Nb2-11 cells to confirm broad applicability, as different cell types may exhibit varying sensitivity based on prolactin receptor expression levels and signaling capacity.
2. Prolactin Receptor Binding Studies
The biologically active prolactin is appropriate for receptor binding studies, and the tag-free design ensures accurate measurement of binding kinetics without tag interference. The high specific activity confirms proper folding for receptor engagement. However, researchers should validate binding characteristics in different tissue-derived receptors, as prolactin receptor isoforms may exhibit varying affinity and signaling properties in different physiological contexts.
3. Antibody Development and Validation
This high-purity, full-length prolactin serves as an excellent antigen for antibody development. However, researchers should note that while the protein maintains biological activity, the E. coli expression produces a non-glycosylated protein, and antibodies should be validated against native rat prolactin from pituitary sources to ensure recognition of glycosylated forms present in physiological conditions. The confirmed bioactivity supports the development of function-blocking antibodies.
4. Biochemical Characterization and Structure-Function Studies
The protein is suitable for biochemical studies, but researchers should acknowledge that the non-glycosylated form may exhibit different stability and aggregation properties compared to native glycosylated prolactin. While the high bioactivity confirms functional integrity, comparative studies with pituitary-derived prolactin should be conducted for comprehensive structure-function analysis, particularly regarding long-term stability and protein-protein interactions.
5. Signal Transduction Pathway Analysis
The biologically active prolactin is appropriate for signaling studies, but researchers should validate pathway activation in physiologically relevant cell types beyond Nb2-11 cells. While JAK-STAT is the primary pathway, prolactin's effects on MAPK and PI3K/Akt may vary by cell context. The low endotoxin ensures specific attribution of signaling events to prolactin activity rather than contaminant-induced pathways.
Final Recommendation & Action Plan
This recombinant rat prolactin is a high-quality reagent suitable for all proposed applications, but researchers should implement validation steps to account for the non-glycosylated nature of the E. coli-expressed protein. For immediate use, employ concentrations in the 0.5-5 ng/ml range based on the ED₅₀, but establish dose-response curves for each specific cell type and endpoint measured. When developing antibodies, validate cross-reactivity with native pituitary-derived prolactin to ensure recognition of physiological forms. For signaling studies, include appropriate controls for pathway specificity and validate key findings in primary cell systems. The tag-free design ensures authentic receptor interactions, but researchers should consider that the non-glycosylated form may exhibit different clearance kinetics and stability in long-term experiments. Always include native prolactin controls when studying complex biological contexts where glycosylation may influence function. The high purity and low endotoxin make this protein particularly valuable for sensitive cell-based assays where minimal stimulation can yield measurable responses.
