Four more examples of symmetric domains. (a) D1dceb_ is the Rab geranylgeranyltransferase b-chain from rat, exhibiting a 6-fold symmetric alpha/alpha toroid structure [28, 29]. Each repeating unit is colored differently to show the 6 repeating units. (b) D1cz5a1 is VAT-N, the N-terminal domain of VAT protein, of the archaebacterium Thermoplasma acidophilum. It has a double psi beta-barrel structure with 2-fold symmetry . The symmetric core of the protein is colored blue for the N-terminal half and red for the C-terminal half. (c) D1uynx_ is the outer membrane translocator domain of an autotransporter from Neisseria meningitidis . Its structure is 12 stranded beta-barrel made of 6 up-and-down beta-hairpins. The ribbon representation is colored in rainbow colors, from blue to red for the N- to C-terminal residues. The symmetry with the highest Z-score is a 2-fold axis. But there are numerous other rotation and screw symmetries with different angles and pitches for this structure. (d) Human ribonuclease inhibitor , d1z7xw1. It has a leucine-rich repeat (LRR) fold. Coloring is rainbow coloring, blue to red from N- to C-terminus.