Expression, purification and functional analysis of rLbRPA-1. Panel A. Analysis of the LbRPA-1 expression in E. coli – M15 cells. Lanes: 1, total cell extract before induction; 2, total cell extract after inducing with IPTG; 3, soluble fraction of the cell extract; 4, insoluble fraction of the cell extract; MW, molecular weight markers. Panel B, Analysis by Coomassie blue staining of the purified rLbRAP-1. Lanes 1 to 4 correspond to sequential fractions of eluted protein after affinity chromatography and in-column refolding procedure. Panel C, functional analysis of the rLbRPA-1 protein. L. braziliensis recombinant α-tubulin (α-tub) or LbRPA-1 were incubated with a digoxigenine labelled oligonucleotide (DIG-O) following the protocol described in Materials and Methods. Dots: 1, amount of DIG-O used in the binding assay; 2, unbound DIG-O; 3–6, DIG-O washed out in sequential washed; 7, eluted protein-DIG-O complexes.