Figure 2.

Variable transcription initiation sites for human L1 elements, as determined by 5′-RACE. Different original L1 constructs (upper part) used in this study were assayed in Tera-1 cells. The determined 5′-ends of transcripts are indicated by arrows. Multiple arrows indicate multiple transcription initiation events at the respective position. No significant differences were observed in mutant constructs (lower part). The various L1 element 5′-ends and upstream flanking sequences are indicated.