EXTRA ADDED: nucleotide-binding fold (rossman fold):
Nucleotide-binding fold (the Rossman fold): it is a domain that is present in many enzymes and is specific for adenosine nucleotides over others. It is a binding motif or supersecondary structure. Area of a protein that binds nucleotides with specificity (as a motif, they are a pattern found in many proteins). It is composed of alternating beta strands (6) and alpha helices (4).