Figure 4.
Structure of the novel class of platypus snoRTEs. snoRTEs are composed of a 5′-H/ACA-snoRNA with the H-box consensus sequence ANANNA and ACA-box sequence (structured part). The sequences that potentially interact with ribosomal or spliceosomal RNA by base complementarities guiding pseudouridylation are indicated (N-ψ). The (gray bar) 3′ part is similar to RTE-elements. Coordinates are given for the BovB_Plat RTE LINE corresponding 145-nt 5′ and 67-nt 3′ sequence regions. [(GACAA)n] Terminal simple repeats; (A4) a spacer sequence between the H/ACA snoRNA and BovB_Plat region. The flanks of the entire snoRTE exhibit (DR) direct repeats. The snoRTE is distributed via retroposition (retro-duplication), is dependent on the host gene RNA polymerase II promoter, and is probably subsequently trimmed in the presence of RTE proteins to a retropositionally active RNA, absence to an H/ACA-box snoRNA.