Apolipoprotein E expression and purification.

Since the discovery of the association of apolipoprotein E (apoE) 4 with Alzheimer's disease 17 years ago, numerous in vitro experiments with the apoE isoforms (apoE2, apoE3, and apoE4) have been performed to try to understand the basis for this association. The majority of these studies used commercial sources for apoE, but some used recombinant protein. In either case, these studies were most often conducted without considering the ramifications of the structural and biophysical differences among the three isoforms or without adequate quality control of the preparations. Here, we present a protocol for producing recombinant apoE that we have used successfully in our laboratory for the last 20 years. We also review the considerations that are critical for obtaining reliable and interpretable results with the end product.