Localized oxidation

Despite their bad reputation, free radicals are also beneficial—they are used as second messengers in proliferation, apoptosis, and migration. Oxidants are promiscuous, however, and must be harnessed to modify only specific proteins. One way specificity is achieved in migration, based on findings from Wu et al. (page 893), is by localizing the oxidase with other motility proteins at the leading edge.

Wu and colleagues found that the NADPH oxidase is localized to focal complexes—transient integrin clusters at the front of migrating cells. The oxidase is brought to these sites by the TRAF4 adaptor and Hic5, a paxillin relative.

Disruption of TRAF4–Hic5 interactions that are expected to delocalize the oxidase reduced cell migration, suggesting that the oxidation of a focal complex protein is necessary for motility. This target turns out to...