The open reading frame of the Na(+)-dependent glutamate transporter GLAST-1 is expressed in bone and a splice variant of this molecule is expressed in bone and brain.

Previously we have reported expression of an mRNA with homology to the Na(+)-dependent glutamate transporter, GLAST-1, in bone. Here we demonstrate that the complete open reading frame of GLAST-1 mRNA and corresponding 69 kDa protein are expressed in rat bone in vivo. We have also discovered a novel splice variant (GLAST-1a), lacking exon 3, expressed in rat bone and brain. A 55 kDa protein detected by anti-GLAST antibody in rat cerebellum corresponds to the molecular weight of unglycosylated GLAST-1a. This has led us to propose that GLAST-1a has an opposite orientation in the cell membrane to GLAST-1.