Cationic amino acid transporter 1-4 (CAT1-4)

The cationic amino acid transporter (CAT) family, comprising CAT-1 (SLC7A1), CAT-2 (SLC7A2), CAT-3 (SLC7A3), and CAT-4 (SLC7A4), consists of integral membrane proteins that facilitate the sodium-independent transport of basic amino acids such as L-arginine, L-lysine, and L-histidine across cell membranes. These transporters are essential for cellular homeostasis, providing substrates for protein synthesis and serving as the primary source of arginine for the production of nitric oxide and polyamines. CAT-1 is ubiquitously expressed and acts as a high-affinity transporter, while CAT-2 exists in two isoforms: CAT-2A (low-affinity, high-capacity, primarily in the liver) and CAT-2B (high-affinity, inducible in macrophages and during inflammation). CAT-3 is predominantly expressed in the brain, and CAT-4 remains largely uncharacterized regarding its transport activity. In clinical contexts, members like CAT-1 and CAT-2 are often overexpressed in various cancers to sustain rapid cell proliferation and are being investigated as potential therapeutic targets. Additionally, CAT-1 serves as the cellular receptor for ecotropic murine leukemia viruses, highlighting its significance in virology. Drugs targeting these transporters aim to modulate nutrient uptake in tumors or control nitric oxide-mediated inflammatory responses.

Other names

SLC7A1SLC7A2SLC7A3SLC7A4Solute carrier family 7 member 1-4System y+ basic amino acid transporterEcotropic retroviral leukemia receptor homologATRC1ATRC2

The cationic amino acid transporters (CATs) function as sodium-independent, pH-insensitive facilitated diffusers that mediate the equilibrative transport (entry and efflux) of basic amino acids across the plasma membrane.