Variability in the immunodetection of His-tagged recombinant proteins.

Labeling of recombinant proteins with polypeptide fusion partners, or affinity tagging, is a useful method to facilitate subsequent protein purification and detection. Poly-histidine tags (His-tags) are among the most commonly used affinity tags. We report strikingly variable immunodetection of two His-tagged recombinant human erythropoietins (Epo): wild type Epo (Epo(wt)) and Epo containing an R103A mutation (Epo(R103A)).

Measurement of hemoglobin in long-term fixed erythroid cells: application development for cell science experiments in microgravity.

Studying the effects of microgravity on cell differentiation will enhance our understanding of fundamental biology and is indispensable for a sustained space program. Rauscher murine erythroleukemic cells were chosen as a model system to study erythroid cell differentiation aboard the International Space Station because these cells undergo differentiation in response to the natural inducer, erythropoietin, as well as various chemical-inducers. We have now developed a method to quantify hemoglobin in Rauscher cells after weeks of fixation and storage required for such space biology experiments.