RNA trans-splicing by 5′ exon replacement generates functional ion channels in human cells. HEK 293T cells were transfected with either target alone (CFTR-T11), PTM alone (CFTR-PTM30), or with target and PTM. Cell populations were incubated in medium containing 125Iodine, and then tested for the presence of ion channel efflux activity (in min−1) by stimulation with forskolin and IBMX at intervals of 3 min (time points 7, 10, 13, and 16 min). Forskolin is predicted to elevate cAMP levels and stimulate cAMP-dependant ion channel activity. Only those monolayers that received a PTM and target showed substantial increases in anion efflux at three time-points (arrows). Values represent mean ± standard error of two independent transfections, with the exception of the 4-min time point for PTM plus target, which represents a single data point. (BD) Binding domain.
