Flavodoxin fold

Ribbon diagram of CheY (a regulator of the chemotactic response in bacteria, PDB accession code 3CHY), which adopts the flavodoxin fold. Ribbon is colored from blue (N-terminus) to red (C-terminus).

The flavodoxin fold is a common α/β protein fold, second only to the TIM barrel fold. It has three layers, with two α-helical layers sandwiching a 5-stranded parallel β-sheet. The order of strands within the sheet is 21345.