A protein complex that is found in the endoplasmic reticulum membrane of eukaryotes and transfers lipid-linked oligosaccharide precursor to asparagine residues on nascent proteins. The complex includes at least eight non-identical subunits. Different forms of the complex containing distinct subunits have been detected in mammals. [ http://www.ncbi.nlm.nih.gov/pubmed/15835887 http://www.ncbi.nlm.nih.gov/pubmed/32316603 http://www.ncbi.nlm.nih.gov/pubmed/31810196 ]