Expression, purification and structural biology of membrane proteins: "affinity purification of membrane proteins"

Abstract

Biochemical, biophysical, and structural studies ofmembrane proteins rely on the availability ofhighly pure and monodisperse membrane protein samples. One of the most powerful methods for isolation of the membrane protein of interest is affinity purification. This methodology typically relies on engineering an affinity tag into the protein ofinterest and an affinity resin that specifically recognizes the tag, allowing one to purify the target protein in a single step. In some cases, the affinity purification procedure is combined with additional steps to increase the purity and homogeneity ofthe final protein sample. Here, we describe several protocols for affinity purification of TSPO, a small membrane protein. The techniques we use include immobilized metal affinity chromatography (IMAC) and strep-II tag-based streptavidin affinity chromatography.