CAT-3 Inhibitors

Chemical inhibitors of CAT-3 effectively reduce its function as an amino acid transporter by employing a variety of competitive and allosteric mechanisms. L-Arginine, L-Lysine, and L-Ornithine act as direct competitors with CAT-3, effectively diminishing its capacity to transport arginine by occupying the binding site. This competition for arginine transport is a key method for the functional inhibition of CAT-3. Similarly, L-Leucine can induce allosteric changes in CAT-3, which can reduce the transporter's affinity for its substrates. Guanidinium chloride is another competitive inhibitor that directly competes with arginine, thereby impeding CAT-3's ability to transport this particular amino acid effectively. α-Methyl-DL-tryptophan also curtails CAT-3 activity by inhibiting the uptake of structurally similar amino acids, while Gabapentin, although primarily targeting GABAergic systems, can inhibit CAT-3 by competing for the transport of specific amino acids.

Furthermore, Cadmium chloride and N-Ethylmaleimide can interact with the thiol groups on CAT-3, which may result in the modification of cysteine residues and consequent inhibition of its amino acid transport function. Diclofenac interferes with the ionic gradients that are essential for CAT-3's activity, leading to inhibition of its transporter function. Verapamil's role as a calcium channel blocker suggests that it can inhibit CAT-3 by altering cellular ionic balances and membrane potentials, which are crucial for the activity of amino acid transporters. Lastly, Methionine sulfoximine competes with glutamine and related amino acids for transport by CAT-3, which can inhibit the protein's transport function.