Verification of formation of αβ heterodimers by gel electrophoresis after cross-linking treatment SDS-PAGE of crosslinked Tm dimers run under oxidising conditions. Lane 1, αα homodimer alone; lane 2, a 1:1 mixture of αα homodimer with αβ heterodimer; lane 3, αβ heterodimer; lane 4, ββ homodimer; lane 5, a 1:1 mixture of ββ homodimer with αβ heterodimer; lane 5, αβ heterodimer. All samples were denatured in 20mM DTT at 60°C, left to cool to 37°C before cross-linking at 20°C via a Cu2+catalysed K3Fe(CN)6 reaction.