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By: Richard D. Cummings Sialic acid is a nonose (9-carbon) monosaccharide found in many organisms. All vertebrates have sialic acid, while most invertebrates do not have sialic acid, but there are notable ones that do, as discussed below. In addition, sialic acid is not generated nor found in...

By: Richard D. Cummings The endoplasmic reticulum (ER) of many types of cells contain members of a family of UDP-glucuronosyltransferases (UGTs). These enzymes utilize uridine diphosphate glucuronic acid (UDP-GlcA) as a donor and add GlcA to a tremendous variety of aglycone hydrophobic compounds...

By: Richard D. Cummings The major urinary glycoprotein is the Tamm-Horsfall protein (THP), also named uromodulin (Umod), and encoded by UMOD (1-4). Its concentration in urine can be as high as 1-2 mg/mL. It was discovered in 1950 by Tamm and Horsfall in their studies on compounds in urine that could...

By: Richard D. Cummings Until a few years ago it was believed that mitochondria do not contain glycoproteins. However, mitochondria contain a variant form of the enzyme UDP-GlcNAc: polypeptide O-β-N-acetylglucosaminyltransferase (OGT) that adds O-GlcNAc to Ser/Thr residues of proteins in...