Troubleshooting framework:
Post-translational modifications: ELISA may detect linear epitopes, while immunofluorescence requires conformational epitopes. Test denatured vs. native protein preparations .
Epitope masking: Use alternative fixation methods (e.g., methanol vs. paraformaldehyde) to expose hidden epitopes.
Quantify target protein levels in lysates via mass spectrometry to establish ground-truth correlations .
Solutions:
Experimental design:
In vitro: Use serum-free medium supplemented with purified complement proteins and compare cell lysis in C02F5.13-expressing vs. knockout cells .
Controls: Include inhibitors of membrane attack complex (MAC) formation (e.g., CD59) to confirm specificity .
Readouts: Measure lactate dehydrogenase (LDH) release and validate via live-cell imaging of membrane integrity.
Recommendations:
Workflow:
For epitope mapping, combine peptide arrays with alanine scanning mutagenesis to identify critical binding residues .
In longitudinal studies, archive aliquots of primary antibodies to control for lot variability.
For quantitative assays, normalize C02F5.13 levels to housekeeping proteins validated in your experimental system (e.g., GAPDH or β-actin) .