Phosphatase Fold Rhodanese
Phosphatase Classification: Fold Rhodanese
Fold CC3 (Rhodanese) has a single superfamily CC3 (Rhodanese).
The CC3 (Cys-based group III) phosphatase superfamily has rhodanese fold catalytic domain, which has the Cx5R catalytic motif shared with the CC1 and CC2 folds. This fold encodes enzymes with a number of redox functions, of which only the CDC25 family has protein phosphatase activitiy.
Not all rhodanese domains have phosphatase activity
Rhodanese domains are ubiquitous structural domains found in both eukaryotes and prokaryotes. It is named after bovine liver rhodanese, the most well characterized sulfurtranferase. The fold and its single superfamily consists of at least ten families based on different domain combinations . The member proteins have various functions and physiological substrates, such as, thiosulfate:cyanide sulfurtransferase, protein phosphatase, and arsenate reductase. The cysteine at catalytic site is necessary for its activity no matter what its substrate is. But, whether the functional specificity is determined solely by catalytic motif is unknown, though it seems different families have different catalytic motif in length and conserved residues .
Rhodanese domains are found as accessory domains in some dual-specificity phosphatases of the CC1 fold. All of these have the catalytic cysteine replaced by aspartate or glutamate, and are believed to be catalytically inactive.