**6. Ubiquinol-cytochrome c oxidoreductase (complex III)**

Phosphorylation has been implicated in the regulation of the Rieske iron-sulfur protein of complex III, which is a major target of ischemia and the decreases in its activity lead to increased superoxide production [37]. Several phosphorylation sites have been identified on the subunits of complex III. The tyrosines on the core subunit 1 of complex III are phosphorylated by the Src kinase family, but the functional consequence of this phosphorylation is not yet known [38]. The role of phosphorylation of Rieske iron-sulfur protein is not clear and it was suggested that it regulates the MPTP opening [37].
