Identification of truncated human glutamate transporter

Excitatory amino-acid carrier 1 (EAAC1) is a high affinity Na+-dependent L-glutamate/D, L-Aspartate transporter protein. A truncated form of EAAC1 (tEAAC1) was identified by reverse transcription and polymerase chain reaction in the human cell line, ACHN, in which EAAC1 mRNA was highly expressed. The deduced amino acid sequence of tEAAC1 lacks 31-77 amino acids including the first extracellular domain. The mRNA encoding tEAAC1 was detected in various cells of human origin but not in cells of rat or mouse origin. The expression of tEAAC1 mRNA was proportional to that of full-length EAAC1 (fEAAC1) mRNA, suggesting common transcriptional regulation between tEAAC1 and fEAAC1. In addition, the expression of EAAC1 mRNA was relatively low or non-existent in non-adherent cells.