2 GLYCINE TRANSPORTER VARIANTS WITH DISTINCT LOCALIZATION IN THE CNS AND PERIPHERAL-TISSUES ARE ENCODED BY A COMMON GENE

We have isolated a cDNA encoding a high affinity, Na+/Cl--dependent gl ycine transporter, GLYT-2, which is distinct from another glycine tran sporter, GLYT-1. While the 3' sequences of these two cDNAs are identic al, the 5' noncoding regions and the N-termini are completely differen t. GLYT-1 is found only in the white matter of the CNS, while GLYT-2 i s found in the gray matter of the CNS as well as in macrophages and ma st cells in peripheral tissues. Our findings suggest that tissue-speci fic alternative splicing or alternative promoter usage from a single g ene results in two mRNA products encoding similar but distinct glycine transporters. The anatomic distibution of GLYT-2 mRNA supports the em erging status of glycine as a supraspinal neurotransmitter and suggest s that glycine may function as a chemical messenger outside the CNS.