Proposed tertiary structure of the HTLV-1 dimer linkage. 4a Stereoview of 3D molecular modelling of a potential structure of the HTLV-1 DIS from nucleotide A730 to A744 using JUMNA (). 4b. Close up of the terminal loop. Bases are coloured as follows: adenine, grey; cytosine, yellow; guanine, orange; and uracil, cyan.