Cell membrane asymmetries and cellular aging.

Saccharomyces cerevisiae, a widely studied unicellular eukaryotic model, multiplies and divides through an asymmetric budding process, where a mother cell produces a smaller daughter cell. Although cells age across successive cell divisions, provided the mother is not too old, each daughter cell inherits a full lifespan potential. Extensive studies in budding yeast have established a framework for understanding how asymmetric cell division contributes to this lifespan resetting. One postulate of this framework is that the capacity of mother cells to bud daughters with full replicative potential is critically dependent on membraneassociated mechanisms that enable asymmetric inheritance of aging factors. Despite the identification of numerous asymmetrically distributed proteins, an integrated catalog detailing their roles in aging has not been compiled. This review provides a comprehensive resource of asymmetrically distributed membrane proteins in yeast that have a role in replicative aging. Existing knowledge governing the establishment and maintenance of asymmetry is synthesized, and gaps in our understanding of how membrane asymmetry contributes to cellular aging are identified.