A, Western blot on GST pulldown products using the indicated constructs. SCCRO and its paralogues were probed for components of the neddylation pathway. All SCCRO paralogues bind to neddylation components. B, Western blot for Cul1 neddylation on products from in vitro neddylation assays supplemented with SCCRO or its paralogues. All paralogues promote neddylation except SCCRO3. C, results from quantitative real-time PCR showing tissue-specific expression of SCCRO and its paralogues. SCCRO expression is disproportionately higher in the testis. D, results from analysis of data from the Genotype-Tissue Expression project showing tissue-specific mRNA expression of SCCRO and its paralogues. SCCRO expression is disproportionally higher in testis compared with other paralogues in other tissues. RPKM, fragments per kilobase of exon per million reads mapped.