Amino acid transport of y+L-type by heterodimers of 4F2hc/CD98 and members of the glycoprotein-associated amino acid transporter family

Amino acid transport across cellular membranes is mediated by multiple transporters with overlapping specificities. We recently have identified the vertebrate proteins which mediate Na+-independent exchange of large neutral amino acids corresponding to transport system L. This transporter consists of a novel amino acid permease-related protein (LAT1 or AmAT-L-lc) which for surface expression and function requires formation of disulfide-linked heterodimers with the glycosylated heavy chain of the h4F2/CD98 surface antigen. We show that h4F2hc also associates with other mammalian light chains, e.g. y+LAT1 from mouse and human which are approximately 48% identical with LAT1 and thus belong to the same family of glycoprotein-associated amino acid transporters. The novel heterodimers form exchangers which mediate the cellular efflux of cationic amino acids and the Na+-dependent uptake of large neutral amino acids. These transport characteristics and kinetic and pharmacological fingerprints identify them as y+L-type transport systems. The mRNA encoding my+LAT1 is detectable in most adult tissues and expressed at high levels in kidney cortex and intestine. This suggests that the y+LAT1-4F2hc heterodimer, besides participating in amino acid uptake/secretion in many cell types, is the basolateral amino acid exchanger involved in transepithelial reabsorption of cationic amino acids; hence, its defect might be the cause of the human genetic disease lysinuric protein intolerance.

Published in:
Embo J, 18, 1, 49-57
Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.

 Record created 2008-02-25, last modified 2018-07-07

Rate this document:

Rate this document:
(Not yet reviewed)