ABC A-subclass proteins: Gatekeepers of cellular phospho- and sphingolipid transport

During the past years, available evidence suggests that members of a novel family of structurally highly related multispan proteins, designated ABC Asubclass transporters, exert critical functions in the control of cellular lipid transport processes. Loss-of-function scenarios, thus far, have revealed pivotal roles of individual ABC A-transporters in specialized lipid secretory pathways of the cell including HDL biogenesis ( ABCA1), lung surfactant production ( ABCA3), retinal integrity ( ABCA4/ ABCR) and skin lipid barrier formation ( ABCA12). Although the specific transporter activities of many members of this novel protein family have not yet been established in detail, available evidence indicates that ABC A-subclass transporters function as key components of highly specialized cellular phospho- and sphingolipid export machineries in major physiologic systems.