Functional heterodimeric amino acid transporters lacking cysteine residues involved in disulfide bond
説明
<jats:p>The protein mediating system L amino acid transport, AmAT‐L, is a disulfide‐linked heterodimer of a permease‐related light chain (AmAT‐L‐lc) and the type II glycoprotein 4F2hc/CD98. The <jats:italic>Schistosoma mansoni</jats:italic> protein SPRM1 also heterodimerizes with <jats:italic>h</jats:italic>4F2hc, inducing amino acid transport with different specificity. In this study, we show that the disulfide bond is formed by heavy chain C109 with a Cys residue located in the second putative extracellular loop of the multi‐transmembrane domain light chain (C164 and C137 for <jats:italic>X</jats:italic>AmAT‐L‐lc and SPRM1, respectively). The non‐covalent interaction of Cys‐mutant subunits is not sufficient to allow coimmunoprecipitation, but cell surface expression of the light chains is maintained to a large extent. The non‐covalently linked transporters display the same transport characteristics as disulfide bound heterodimers, but the maximal transport rates are reduced by 30–80%.</jats:p>
収録刊行物
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- FEBS Letters
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FEBS Letters 439 (1-2), 157-162, 1998-11-13
Wiley