Added PubMed Id Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect human cells by first attaching to the ACE-2 receptor via its receptor-binding domain (RBD) in the spike protein. We investigated the influence of N-glycosylation sites of the RBD and the membrane (M) protein on IgG antibody binding in serum samples from patients infected with the original SARS-CoV-2 strain in Germany. The N-glycosylation sites Asn331, Asn334, Asn343, Asn370 and Asn381 of RBDs of the wildtype, alpha, beta, gamma, kappa, and omicron BA.1 variants expressed in HEK293T and HEK293S GnTI- cells , as well as Asn5 for the M-protein were analyzed with tandem mass spectrometry for N-glycosylation.