At the time, pfcrt was (to our knowledge) the largest synthetic gene ever constructed by overlapping PCR, nonetheless, success enticed others to attempt the reconstruction of a yeastoptimized pfmdr1 gene, which is over three times the size of pfcrt. After numerous challenges were overcome, this too was achieved and unusual ATPase activity of PfMDR1 was rather quickly quantified via plate-based phosphate release assays [88] . Relative to other ABC transporters involved in drug-resistance phenomena, PfMDR1 has unusually high K m and V max for ATP hydrolysis. Also, interestingly, antimalarial drugs only mildly stimulated PfMDR1 ATPase activity, consistent with the notion that PfMDR1 exerts only mild affects on antimalarial drug resistance. With methods for in vitro future science group analysis of PfMDR1 in hand, a follow-up study quickly defined which amino acid substitutions in the curious 7G8 PfMDR1 isoform confer its unusual and quite specific ATPase activity [89] . The S1034C mutation in 7G8 PfMDR1 is now known to abolish antimalarial drug-stimulated PfMDR1 ATPase activity. Although this molecular-level work is only just beginning, it has already significantly refined proposals for the molecular mechanisms of CQ resistance and antimalarial multidrug resistance.