Recognition of the Ub-like domain

The crude mimicking of an Ub-dimer could potentially contribute to its specific recognition by delSGylating enzymes. 

The central feature that defines all DUBs is that they recognize and act at the C-terminus of the ubiquitin or ubiquitin-like domain. All mature ubiquitin and ubiquitin-like proteins have a C-terminal gly-gly motif and DUB cleavage releases leaving groups attached to the carboxyl group of the C-terminal glycine. With the exception of the JAMM metalloproteases, DUB catalysis starts with the nucleophilic attack of the catalytic cysteine on the carbonyl carbon of the scissile bond to 

In principle, DUBs might also recognize the leaving group to which ubiquitin is attached. In fact, such a mechanism seems likely as several DUBs have little affinity for ubiquitin and several have been shown to bind the un-ubiquitinated target protein (see Table 8.2). Interactions between DUBs and putative substrates have been shown for the mammalian DUBs VDUl, USPll, and UBPy, as well as UBP3 from yeast and fat facets from Drosophila [64-68]. In other cases, DUB-binding proteins may serve as scaffolds or adaptors that localize DUBs (discussed below). 

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