Structure of the DIRS1 reference element identified in the slime mold Dictyostelium discoideum. The three ORFs encoding the GAG, tyrosine recombinase (YR) and pol (Reverse Transcriptase (RT) - RNase H (RH) - MethylTransferase (MT) domain series) regions correspond to shaded boxes. The two Inverted Terminal Repeats (ITRs) are represented by the outer triangles. The two Internal Complementary Regions (ICRs) correspond to the inner triangles. The rE at the 3'-end of the element is represented by the red box. The positions of the three alignment profiles used to screen for DIRS1-like elements among genomes are symbolized by black bars under their respective domains (RT-, MT- and YR-encoding domains).