| Feature | TURN |
| Definition | Secondary structure Turns, for example, H-bonded turn (3-turn, 4-turn or 5-turn) |
| Optional Qualifiers |
/NOTE="free text" |
| Comment | This feature is used only for proteins whose tertiary structure is known. Only three types of secondary structure are specified: helices (key HELIX), beta-strands (key STRAND) and turns (key TURN). Residues not specified in one of these classes are in a "loop" or "random-coil" structure. |