Figure 5.

(A) Investigation of regulatory signals within COX V, VI and IX 3′-UTRs. The intergenic region for each COX subunit was positioned downstream of the CAT gene, this being encompassed within a construct comprising a phleomycin resistance gene and targeted to integrate into the tubulin gene array. The site of polyadenylation is indicated within the intergenic region (denoted ‘A’). At least two stable cell lines were generated for each construct and two independent CAT assays performed on cell extracts from each cell line. (B) Resulting CAT expression for each COX intergenic region deletion are shown as a percentage of the CAT expression from an identical construct comprising a deleted aldolase gene 3′-UTR, which provides constitutive expression in bloodstream and procyclic forms. The CAT mRNA abundance for each construct is shown at the extreme right, as a percentage of the CAT mRNA abundance derived from constructs comprising each intact COX subunit intergenic region (IR). These values were derived from northern blots, representatives of which are shown in Figure 6.