Cytochrome c urate oxidase (Uox) PuuD is involved in purine degradation. In contrast with soluble Uox it is a membrane protein with an 8-helix transmembrane N-terminal domain and a C-terminal cytochrome c [1].

1: The identification of an integral membrane, cytochrome c urate oxidase completes\tthe catalytic repertoire of a therapeutic enzyme. Doniselli N, Monzeglio E, Dal Palu A, Merli A, Percudani R; Sci Rep. 2015;5:13798. PMID:26349049