Differential Influence of the 4F2 Heavy Chain and the Protein Related to b0,+ Amino Acid Transport on Substrate Affinity of the Heteromeric b0,+ Amino Acid Transporter

• Published in: The Journal of biological chemistry 2000-05, Vol.275 (19), p.14331-14335
• Main Authors: Rajan, D.Prasanna, Huang, Wei, Kekuda, Ramesh, George, Ronald L., Wang, Jian, Conway, Simon J., Devoe, Lawrence D., Leibach, Frederick H., Prasad, Puttur D., Ganapathy, Vadivel
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.275.19.14331

We provide evidence here that b0,+ amino acid transporter (b0,+AT) interacts with 4F2 heavy chain (4F2hc) as well as with the protein related to b0,+ amino acid transporter (rBAT) to constitute functionally competent b0,+-like amino acid transport systems. This evidence has been obtained by co-expression of b0,+AT and 4F2hc or b0,+AT and rBAT in human retinal pigment epithelial cells and in COS-1 cells. The ability to interact with 4F2hc and rBAT is demonstrable with mouse b0,+AT as well as with human b0,+AT. Even though both the 4F2hc·b0,+AT complex and the rBAT·b0,+AT complex exhibit substrate specificity that is characteristic of system b0,+, these two complexes differ significantly in substrate affinity. The 4F2hc·b0,+AT complex has higher substrate affinity than the rBAT·b0,+AT complex. In situ hybridization studies demonstrate that the regional distribution pattern of mRNA in the kidney is identical for b0,+AT and 4F2hc. The pattern of rBAT mRNA expression is different from that of b0,+AT mRNA and 4F2hc mRNA, but there are regions in the kidney where b0,+AT mRNA expression overlaps with rBAT mRNA expression as well as with 4F2hc mRNA expression.