The general tRNA tertiary structure (and the secondary structure in the box). Four helices (in acceptor, D-arm, TΦC arm, and anticodon arm) enclose loops, including the variable loop (orange), possibly long in some tRNAs. The helix of acceptor (purple) and the helix of TΦC arm (green) coaxially stack (in the nested fashion); the helix of D-arm (red) and the helix of anticodon arm (blue) coaxially stack (in the parallel fashion). Figure modified from Rfam .
Shareghi et al. BMC Genomics 2012 13(Suppl 3):S7 doi:10.1186/1471-2164-13-S3-S7