Flavodoxin fold

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.

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).