The<unk>  is a protein structural motif found in proteins that bind nucleotides, especially the cofactor NAD. The structure is composed of three or more parallel beta strands linked by two alpha helices in the topological order beta-alpha-beta-alpha-beta. Because each<unk>  can bind one nucleotide, binding domains for dinucleotides such as NAD consist of two paired<unk> s that each bind one nucleotide moiety of the cofactor molecule. Single<unk> s can bind mononucleotides such as the cofactor FMN.
The motif is named for Michael<unk>  who first pointed out that this was a frequently occurring motif in nucleotide binding proteins.
Rossmann fold
Vocal folds
Epicanthal fold
Clitoral crura
Veratrum
Ranula
Pinguecula
Phrygian cap