The amino acid transport system y+L/4F2hc is a heteromultimeric complex

• DOI: 10.1096/fasebj.12.13.1319
• Publication Date: 2018-01-18T12:01:00Z
• Authors: Raúl Estévez; Marta Camps; Ana María Rojas; Xavier Testar; Rosa Devîs; Matthias A. Hediger; Antonio Zorzano; Manuel Palacín
• Keywords: 0301 basic medicine; Oocyte; Macromolecular Substances; Protein Conformation; Recombinant Fusion Proteins; Fusion Regulatory Protein-1; Homologous protein; Xenopus laevis; 03 medical and health sciences; Antigens, CD; Animals; Humans; Cysteine; Amino Acids; Mercaptoethanol; Y+L transport activity; Biological Transport; Erythrocyte; Gene Expression Regulation; Mutagenesis; Mercuric Chloride; Mutagenesis, Site-Directed; Oocytes; RNA; Carrier Proteins; 4-Chloromercuribenzenesulfonate; Protein Processing, Post-Translational

4F2hc is an almost ubiquitous transmembrane protein in mammalian cells; upon expression Xenopus laevis oocytes, it induces amino acid transport with characteristics of system y+L. Indirect evidence fostered speculation that function requires the association another endogenous to oocytes and native tissues. We show y+L-like activity by limited factor direct covalent modification external cysteine residue(s) oocyte membrane blocks y+ L/4F2hc activity, based on following. 1) Induction saturates at very low doses human cRNA (0.1 ng/oocyte). This saturation occurs surface, further increased cell surface does not result higher induction activity. 2) Human contains only two residues (C109 C330). mutated these residues, singly combination, serine (C109S; CS1, C330S; CS2 C109S-C330S, Cys-less). Mutation had no effect expressed L-like whereas C109S-containing mutants (CS1 Cys-less) retained partial (30 50% wild type). 3) Hg2+, organic mercury compounds pCMB, membrane-impermeant p-CMBS completely inactivated induced type all studied. was reversed β-mercaptoethanol, indicating are target this inactivation. 4) Sensitivity Hg2+ inactivation pretreatment β-mercaptoethanol or The reactivity supports possibility C109 may be linked a disulfide bond Hg2+-targeted residue associated protein. These results indicate intimately for y+L To our knowledge, first heteromultimeric structure solute carrier mammals.— Este´vez, R., Camps, M., Rojas, A. Testar, X., Deve ´s, Hediger, M. A., Zorzano, Palacı´n, y/L/4F2hc complex. FASEB J. 12, 1319–1329 (1998)