The structural characteristics of Helentrons and their non-autonomous partners from other species. The open black box denotes the ORF encoding the Rep/Helicase protein (the lighter green is the Rep, the medium green is the helicase, and the endonuclease is the darker olive shade). The orange block denotes the ORF encoding the RPA protein. The histone gene and gene fragments are represented in pink. The green arrows represent the subterminal repeats (subTIRs). The red stem loop structure represents the 3' palindrome. The green sideways triangle in the 5' end represents the 3' side of the inverted repeat (IR) (the 5' side is nested inside the 5' subTIR). The red T represents the flanking host sequence. Black vertical and horizontal lines point to the pairwise sequence identities and length of alignment (excluding gaps) of the sequences compared. (A-D) The structures of select Helentrons (Helentron-Cq-32A.4 and Helentron-Cq-31A.1) and their non-autonomous partners (HINE-Cq-32A.1 and HINE-Cq-31A.1) from the Culex quinquefasciatus genome. (E, F) The structure of another Helentron family (Helentron-Da-40A.1) from D. ananassae and the non-autonomous partner (DINE-Da-40A.1) described in . The putative Rep/Helicase/Endonuclease in this Helentron is in the opposite orientation relative to others. (G-J) The structure of a novel family of Helentron (Helentron-Da-41A.1, Helentron-Dw-41B.1) present in both Drosophila ananassae and D. willistoni genomes and the non-autonomous partners (HINE-Da-41A.1, HINE-Dw-41B.1).