Facilitative glucose transporter required for the development of the cardiovascular system. D-glucose(out) = D-glucose(in) Expressed both maternally and zygotically (PubMed:21553381). Ubiquitous expression until the early somitogenesis stage (PubMed:21553381). In later embryonic stages, detected in the otic vesicles, hatching gland cells, pectoral fin, posterior tectum and swim bladder (PubMed:21553381). Morpholino knockdown of the protein causes notochord and cardiovascular abnormalities (PubMed:22116938). Fishes display a reduced heart rate and blood flow, coupled with an incomplete and irregular vascular patterning (PubMed:22116938). Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family. Glucose transporter subfamily.