The WSAWS motif is C-hexosylated in a soluble form of the erythropoietin receptor.
The WSXWS motif is a highly conserved structural feature of the type I cytokine receptor family. It has previously been demonstrated that mutations in the (232)WSAWS(236) motif in the erythropoietin receptor (EPOR) can result in strongly inhibited surface expression, due to defective intracellular transport [Hilton, D. J., et al. (1996) J. Biol. Chem. 271, 4699-4708]. Here we report that the first tryptophan in the motif of the recombinant extracellular domain of EPOR (sEPOR) expressed in HEK-EBNA cells carries a C-linked hexosyl residue. The S233A mutation completely abolished secretion of sEPOR, whereas the A234E mutation resulted in enhanced secretion. Comparison of the level of C-hexosylation in the wild-type protein and in the mutant proteins isolated from the conditioned medium and/or the cells suggested that C-hexosylation of the motif did not play a role in the correct intracellular transport of sEPOR.
Furmanek
Aleksandra
A
Friedrich Miescher Institute, Novartis Research Foundation, Maulbeerstrasse 66, 4058 Basel, Switzerland.
Hess
Daniel
D
Rogniaux
Hélène
H
Hofsteenge
Jan
J
D019943:Amino Acid Substitution; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005822:Genetic Vectors; D006601:Hexoses / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D021381:Protein Transport; D017467:Receptors, Erythropoietin / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D012995:Solubility
D006601:Hexoses; D009842:Oligopeptides; D010446:Peptide Fragments; D017467:Receptors, Erythropoietin; D011994:Recombinant Proteins