title: Defective Ca(2+) binding in a conserved binding site causes incomplete N-glycan processing and endoplasmic reticulum trapping of discoidin domain receptors.
abstract: An X-ray crystallographic study has suggested that vertebrate discoidin domain receptors (DDRs) have a conserved Ca(2+) binding site. DDR1 and DDR2 transfected in HEK293 cells were expressed mainly as 120 and 130 kDa forms, respectively, as they are sufficiently N-glycosylated. However, both of them showed the molecular weight of 110 kDa predominantly in the cells cultured with Ca(2+)-depleted media. DDR2-carrying D234A mutation at the conserved Ca(2+)-binding site expressed the 110 kDa form dominantly even in normal culture condition. DDR2 becomes 100 kDa form in glucose-depleted culture condition and its molecular weight increases up to 130 kDa with re-feeding glucose. However, in the mutant DDR2, the increase came to a halt at 110 kDa. The 110 kDa form had premature N-glycosyl carbohydrates and located predominantly within the endoplasmic reticulum. These results suggest that DDRs require Ca(2+)-binding to complete their N-glycan processing and generate the form targeted to cell membrane.
authors.affiliation: a Chemical Kinomics Research Center , Korea Institute of Science and Technology , Seoul , Korea.
authors.forename: Trong-Nhat
authors.initials: TN
authors.lastname: Phan
authors.forename: Ee Lin
authors.initials: EL
authors.lastname: Wong
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Park
authors.forename: Hae Jong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Beom-Seok
authors.initials: BS
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D000070819:Discoidin Domain Receptor 1; D000070818:Discoidin Domain Receptors; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006031:Glycosylation; D057809:HEK293 Cells; D006388:Hemagglutinins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011975:Receptors, Mitogen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D006388:Hemagglutinins; D011134:Polysaccharides; D011975:Receptors, Mitogen; D011993:Recombinant Fusion Proteins; C092030:DDR1 protein, human; D000070819:Discoidin Domain Receptor 1; D000070818:Discoidin Domain Receptors; C512478:EGFR protein, human; D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; D002118:Calcium
keywords: calcium binding; discoidin domain receptor; endoplasmic reticulum; posttranslational modification