Oocytes in mammals are formed in the female fetus and are not replenished after birth, so they have to be maintained until and throughout reproductive life. How oocytes (and their supporting somatic cells in the ovary) maintain a functional proteome during this long period is unknown. Harasimov et al. now show that proteostasis is particularly potent in ovary cells.

Protein longevity was examined in the entire ovary (oocytes and somatic cells), from birth up to 65 weeks of age. The half-life of most proteins in the ovary was approximately 8–10 days, similar to protein turnover in other organs. However, >10% of the proteins had half-lives of above 100 days; by comparison, less than 1% of proteins in other organs exhibited such longevity. Notably, many extremely long-lived proteins persisted in the ovary until the end of the experiment, which encompassed almost the entire lifespan of these females. The extremely long-lived ovary proteins had essential functions in proteostasis, mitochondria, chromatin and as antioxidants, among others.