The small SLC43 family: facilitator system l amino acid transporters and the orphan EEG1

Mol Aspects Med. Apr-Jun 2013;34(2-3):638-45. doi: 10.1016/j.mam.2012.12.006. Epub 2012 Dec 23.

Abstract

The SLC43 family is composed of only three genes coding for the plasma membrane facilitator system l amino acid transporters LAT3 (SLC43A1; TC 2.A.1.44.1) and LAT4 (SLC43A2; TC 2.A.1.44.2), and the orphan protein EEG1 (SLC43A3; TC 2.A.1.44.3). Besides the known mechanism of transport of LAT3 and LAT4, their physiological roles still remain quite obscure. Morphants suggested a role of LAT3 in renal podocyte development in zebrafish. Expression in liver and skeletal muscle, and up-regulation by starvation suggest a role of LAT3 in the flux of branched-chain amino acids (BCAAs) from liver and skeletal muscle to the bloodstream. Finally, LAT3 is up-regulated in androgen-dependent cancers, suggesting a role in mTORC1 signaling in this type of tumors. In addition, LAT4 might contribute to the transfer of BCAAs from mother to fetus. Unfortunately, the EEG1 mouse model (EEG1(Y221∗)) described here has not yet offered a clue to the physiological role of this orphan protein.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Transport System y+L / genetics*
  • Amino Acid Transport System y+L / metabolism
  • Amino Acid Transport System y+L / physiology*
  • Amino Acid Transport Systems / metabolism
  • Amino Acid Transport Systems, Basic / metabolism
  • Amino Acids / metabolism*
  • Blotting, Northern
  • Humans
  • Liver / metabolism
  • Mechanistic Target of Rapamycin Complex 1
  • Models, Molecular*
  • Multigene Family / genetics*
  • Multiprotein Complexes / metabolism
  • Muscle, Skeletal / metabolism
  • Neoplasm Proteins / genetics*
  • Neoplasm Proteins / metabolism
  • Neoplasm Proteins / physiology*
  • Podocytes / metabolism
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Amino Acid Transport System y+L
  • Amino Acid Transport Systems
  • Amino Acid Transport Systems, Basic
  • Amino Acids
  • Multiprotein Complexes
  • Neoplasm Proteins
  • SLC43A1 protein, human
  • SLC43A3 protein, human
  • SLC7A6 protein, human
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1