Native MS reveals the oligomeric state distribution of AM2. (A) The sequence of AM2 with the short extra-viral domain colored in yellow, the transmembrane domain in pink, and the intra-viral region in blue. (B) A schematic of ESI with CID to remove detergent from AM2, (C) the mass spectrum of AM2 (at 50 μM per monomer) in C8E4 detergent at pH 5, (D) the deconvolved mass spectrum, and (E) the extracted normalized peak areas of each oligomeric state.