Plasma membrane ABC transporters serve dual functions in the cell: they export toxins to protect against damage and morphogens to mediate communication. It is thought that the activity of ABC transporters in embryos and stem cells should be high, so that mutagens are efficiently removed. Here, Joseph Campanale and Amro Hamdoun () report the surprising finding that ABC transporter activity is reduced in germline precursors, the small micromeres, of the sea urchin embryo. This reduction in efflux pump activity can likely be ascribed to an increase in the rate of endocytosis specifically in the micromeres. What are the functional consequences of manipulating ABC transporter activity? The authors take a first step towards understanding this, showing that ABC transporter inhibition disrupts migration of the small micromeres at later stages of embryogenesis. While there is still much to be understood about the regulation and role of these plasma membrane pumps, this study provides evidence for the developmental importance of controlling their surface expression and activity.
