SDS-PAGE analysis of U24 purified from C41(DE3), Origami 2 and SHuffle E.coli , in the presence and absence of β-mercaptoethanol reducing agent. Isolated U24 was from indicated strains, cultured in LB media. Protein solution was mixed 1:1 (vol:vol) with 2X SDS-PAGE buffer ± 2.5% β-mercaptoethanol (βME) final concentration, and analysis carried out by Tris-Tricine SDS-PAGE. Protein amounts were approximately as follows: U24C41(DE3) , 0.1 μg; U24Origami2 and U24SHuffle, 0.4 μg. M: molecular markers. Arrow points to location of monomeric U24 (10.2 kDa); * indicates U24 dimer.