Fig. (8) Random mutagenesis of HT2 resulted in improved soluble and functional expression of fusions to Rluc. Rluc fusions (69 kDa) to HT2, HT2(GNF), codon-optimized (co) HT2(GNF), HT2.1, and HT3 were overexpressed in E. coli KRX at 30 °C and then lysate fractions containing total (T) or soluble (S) protein were labeled to completion with the TMR-ligand and resolved by SDS-PAGE. Gels were imaged for both total protein (SimplyBlue, panel A) and the amount of functional fusion (TMR fluorescence, panel B). Overlaid arrows indicate bands of interest. Note the ~34 kDa band in panel B which presumably represents truncation of the fusion.