Schematic depiction of S-layer glycoprotein glycans from Gram-positive and Gram-negative bacteria and archaea and of SCWPs of Gram-positive bacteria. Ac, CH3COO−; CONH2, amidyl-; -COOMe, methyl ester; Me, CH3-; NAc, N-acetyl-; P, phosphate; Pyr, pyruvyl; R1, -COOH; R2, -CONHAc; R3, -CONAc2, S, sulfate;. Sugar symbols:◯, hexose;, hexuronic acid;, glucose;, N-acetylglucosamine;, glucuronic acid;, 3-N-acetylquinovosamine;, 2,3-di-N-acetylglucuronic acid;, 6-sulfoquinovose;, 2-amino-6-sulfo-2,6-dideoxy-quinovose;, galactose;, galactofuranose;, N-acetylgalactosamine;, galacturonic acid;, 3-O-methylgalacturonic acid;, mannose;, N-acetylmannosamine;, mannosaminuronic acid;, 6-N-amido-Thr mannosaminuronic acid;, l-rhamnose;, d-rhamnose;, l-fucose;, d-fucose;, 3-N-acetylfucosamine;, iduronic acid;, ribose;, d-glycero-d-manno-heptose;, xylose;, digitoxose;, 5-acetamidino-7-glycerolyl pseudaminic acid;, N-acetylmuramic acid. Monosaccharide symbols follow the SNFG (Symbol Nomenclature for Glycans) (Appendix-1B 2015). (Mescher and Strominger 1976; Koval and Jarrell 1987; Lechner and Sumper 1987; Sumper et al. 1990; Altman et al. 1991, 1992, 1995, 1996; Baumeister and Lembcke 1992; Christian et al. 1993; Kärcher et al. 1993; Möschl et al. 1993; Bock et al. 1994; Messner et al. 1995; Kosma et al. 1995a,b; Meier-Stauffer et al. 1996; Schäffer et al. 1999a,b, 2000a,b, 2004; Eichler 2000, 2013; Steindl et al. 2002, 2005; Pfoestl et al. 2003; Kählig et al. 2005; Voisin et al. 2005; Steiner et al. 2008; Veith et al. 2009; Peyfoon et al. 2010; Posch et al. 2011; Messner, Schäffer and Kosma 2013; Palmieri et al. 2013; Kandiba and Eichler 2014; Parente et al. 2014; Anzengruber et al. 2014a; Appendix-1B 2015; Lu et al. 2015; Kandiba et al. 2016). (Extended and modified from Eichler 2013. With permission from Nature Publishing Group).