Figure 1: Mechanism of 3′ transduction by the L1 retrotransposon, based on the results of Moran et al.2.

Read-through transcription by RNA polymerase leads to movement of the DNA that flanks L1. The signal for terminating transcription through L1 is either the weak cleavage/polyadenylation signal of L1 itself (a), or a stronger polyadenylation signal in the 3′ flanking DNA (b). When the resulting complementary DNA integrates into a new genomic locus (green), a simple L1 insertion (a), or a chimaeric insertion (b) is formed. Purple arrows, polyadenylation signals.