However, the dietary CP levels did not influence expression of the neutral AAT ASCT1 and acidic AAT EAAT3 in the colon (Fig.
Reducing protein concentration in dietary will not affect the ASCT1 and EAAT3 expression, which implied low protein could also guarantee amino acid absorption.
A number of HATs amino acid transporters have been isolated since the end of last century, which are the [Na.sup.+]-dependent system ASCT1
(Arriza et al., 1993), the [Na.sup.+]-dependent system [B.sup.0+] (Kekuda et al., 1996; Kekuda et al., 1997), the [Na.sup.+]-independent system L (Mastroberardino et al., 1998), the system N (Chaudhry et al., 1999) as well as to the system A (Varoqui et al., 2000).
The invention is directed toward the isolation, characterization and pharmacological use of the human amino acid transporter proteins EAAT1, EAAT2, EAAT3 and ASCT1
. The invention specifically provides isolated complementary DNA copies of mRNA corresponding to each of these transporter genes.