An amphipol-stabilized multi-pass transmembrane protein as an immunogen to generate mouse memory B cells against native VMAT2

Complex integral membrane proteins with the property of multiple
transmembrane-spanning regions are large protein families, including
G-protein-coupled receptors (GPCR), ion channels, and transporters. Due to
their essential roles in sensing and processing signals, they are the
primary drug targets of more than half of the approved drugs—majorly small
molecules. Although antibodies succeeded in the pharmaceutical markets,
they are rare in modulating complex integral membrane proteins with
favorable properties. Two significant limitations in such antibody
discovery are the preparation of correctly folded antigens and the
generation of antibodies against the natural conformation. Here, we
developed an amphipol-trapped antigen as an immunogen and induced
efficient mouse memory B cell responses. We generated antibodies
unbiasedly by culturing single memory B cells and characterized their
specificities. We implemented our strategy to generate high-affinity
antibodies against the native conformation of vesicular monoamine
transporter 2 (VMAT2), demonstrating the potential use in discovering
antibodies against membrane proteins, including multi-pass transmembrane
protein, for therapeutics.