Studies of substrate binding region of mEAAC1 and mASCT1 by constructing chimeras

The cDNA chimeras between two subtypes of mouse excitatory amino acid trans porter family, mouse excitatory amino acid carrier 1 (mEAAC1) and mouse ala nine serine cysteine transporter 1 (mASCT1), were constructed by recombinan t PCR. After transcription in vitro, the cRNA was injected and expressed in Xenopus laevis oocytes. H-3-Glu and H-3-Ser were used as isotopic tracer t o measure the flux of amino acids. The results showed that there might not be the key amino acids responsible for substractive specificity in the NH2- terminal and its adjacent regions of these two transporters, which probably supported the formation of the substrate binding sites.