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. 2023 Feb 27;324(4):C799–C806. doi: 10.1152/ajpcell.00555.2022

Figure 1.

Figure 1.

Structure of the alveolar epithelial glycocalyx. The epithelial glycocalyx is a layer of glycosaminoglycans (GAGs) that line the epithelial surface. Heparan sulfate (HS) is a linear polysaccharide composed of repeating units of glucosamine and a hexuronic acid (either glucosamine or its epimer, iduronic acid). Chondroitin sulfate (CS) is a linear polysaccharide composed of repeating units of galactosamine and a hexuronic acid. Both HS and CS are attached to a proteoglycan backbone and can be sulfated at specific sites as indicated. Hyaluronic acid (HA) is a linear polysaccharide that is composed of galactosamine and glucuronic acid. It binds to cluster differentiation 44 (CD44) and is not covalently linked to proteoglycans of the epithelial surface and is not sulfated. Gal, galactosamine; GalNAc, N-acetyl galactosamine; GlcA, glucuronic acid; GlcNAc, N-acetyl glucosamine; IdoA, iduronic acid; Xyl, xylulose. The schematic figure was created using BioRender.