The role of N-glycosylation in transport function and surface targeting of the human solute carrier PAT1.
In the present study we show in the Xenopus laevis expression system that the proton-coupled amino acid transporter 1 (PAT1, SLC36A1) is glycosylated at asparagine residues N174, N183 and N470. To determine the functional role of N-glycosylation, glycosylation-deficient mutants were analyzed by two-electrode voltage-clamp measurements after expression in X. laevis oocytes. Single replacements of asparagine residues had no effect on transport activity. However, multiple substitutions resulted in a decreased transport rate, leaving K(t) unchanged. Immunofluorescence localisation revealed a diminished plasma membrane expression of glycosylation-defective mutants. This indicates that N-glycans are not required for transport function, but are important for membrane targeting.
Dorn
Madlen
M
Institute of Biochemistry/Biotechnology, Faculty of Science I, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
Jaehme
Michael
M
Weiwad
Matthias
M
Markwardt
Fritz
F
Rudolph
Rainer
R
Brandsch
Matthias
M
Bosse-Doenecke
Eva
E
D026905:Amino Acid Transport Systems / Q000378:metabolism*; D000818:Animals; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D006801:Humans; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D021381:Protein Transport / Q000502:physiology; D027981:Symporters / Q000378:metabolism*
D026905:Amino Acid Transport Systems; C475905:SLC36A1 protein, human; D027981:Symporters