Lipid transporter that specifically mediates export of sphingosine-1-phosphate (sphing-4-enine 1-phosphate, S1P) and sphinganine-1-phosphate, which play critical roles in regulating heart development (PubMed:19062281, PubMed:19074308). Mediates the export of S1P from cells in the extraembryonic yolk syncytial layer (YSL), thereby regulating myocardial precursor migration (PubMed:19062281, PubMed:19074308). sphing-4-enine 1-phosphate(in) = sphing-4-enine 1-phosphate(out) sphinganine 1-phosphate(in) = sphinganine 1-phosphate(out) Induced at the marginal cells of the blastoderm at dome stage. During gastrulation stages, it is predominantly expressed in the extraembryonic yolk syncytial layer (YSL) with a dorsal-to-ventral gradient. Expression in the YSL is strongly detected just below the developing myocardial precursors and maintained throughout segmentation period. This expression continues through early somitogenesis. However, as somitogenesis proceeds, expression domains become evident in the somitic mesoderm and in the endoderm adjacent to the yolk extension. By 24 hpf, it is strongly expressed in a distinct compartment of the somites, in the endoderm, and in the heart. Disrupted formation of the primitive heart tube. Belongs to the major facilitator superfamily. Spinster (TC 2.A.1.49) family.