InterPro domain: IPR016193

This superfamily represents a structural domain with a core fold consisting of alpha-beta(2)-(alpha-beta)2 that folds into three layers (alpha/beta/alpha); some members may contain an extra C-terminal strand. This domain is found in several types of proteins, including:

• Cytidine deaminase ( 3.5.4.5 ), including both mono-domain enzymes [ 1 ] and two-domain enzymes that arose through a duplication and which contain extra helices in the N-terminal domain [ 2 ].
• Deoxycytidylate (dCMP) deaminase ( 3.5.4.12 ) [ 3 ].
• Guranine deaminase GuaD ( 3.5.4.3 ) [ 4 ].
• Cytosine deaminase ( 3.5.4.1 ) [ 5 ].
• AICAR transformylase domain ( 2.1.2.3 ) of the bifunctional purine biosynthesis enzyme ATIC; this protein consists of two domains of this fold with extra secondary structures within and in between the two core motifs [ 6 ].
• Hypothetical protein TM1506 from Thermotoga maritima also contains a domain of this structure.

1. Structure of human cytidine deaminase bound to a potent inhibitor. J. Med. Chem. 48, 658-60
2. Cytidine deaminase complexed to 3-deazacytidine: a "valence buffer" in zinc enzyme catalysis. Biochemistry 35, 1335-41
3. Three-dimensional structure of the R115E mutant of T4-bacteriophage 2'-deoxycytidylate deaminase. Biochemistry 43, 13715-23
4. Crystal structure of Bacillus subtilis guanine deaminase: the first domain-swapped structure in the cytidine deaminase superfamily. J. Biol. Chem. 279, 35479-85
5. Heart rates in the captive, free-ranging beaver. null 91, 431-5
6. Crystal structure of a bifunctional transformylase and cyclohydrolase enzyme in purine biosynthesis. Nat. Struct. Biol. 8, 402-6