EAT-4, a homolog of a mammalian sodium-dependent inorganic phosphate cotransporter, is necessary for glutamatergic neurotransmission in Caenorhabditis elegans

The Caenorhabditis elegans gene eat-4 affects multiple glutamatergic neurot ransmission pathways. We find that eat-4 encodes a protein similar in seque nce to a mammalian brain-specific sodium-dependent inorganic phosphate cotr ansporter I (BNPI). Like BNPI in the rat CNS, eat-4 is expressed predominan tly in a specific subset of neurons, including several proposed to be gluta matergic. Loss-of-function mutations in eat-4 cause defective glutamatergic chemical transmission but appear to have little effect on other functions of neurons. Our data suggest that phosphate ions imported into glutamatergi c neurons through transporters such as EAT-4 and BNPI are required specific ally for glutamatergic neurotransmission.