SINEUP modular structure. SINEUP binding domain (circled area): SINEUP sequence that overlaps, in antisense orientation, to the sense protein-coding mRNA (target mRNA). SINEUP effector domain: non-overlapping portion of SINEUPs, containing the inverted SINEB2 element (invB2, red) that confers activation of protein synthesis. 5′ to 3′ orientation of sense and antisense RNA molecules is indicated. Flexibility of SINEUP design is indicated.