Recognition markers, carbohydrates

Several laboratories have studied the assimilation of specific lysosomal enzymes using as model systems skin fibroblasts deficient in the enzyme under study. The underlying mechanism for the translocation of lysosomal enzymes was hypothesized to involve binding of carbohydrate-containing recognition markers to specific cell surface receptors (1 5). In support of this hypothesis Hickman, Shapiro, and Neufeld (16J found that treatment of N-acetyl-B-hexosaminidase with periodate under conditions that dTd not affect enzymatic activity prevented the efficient assimilation of this enzyme by Sandhoff fibroblasts. Additionally, Kresse and von Figura (1 7) found that treatment of f -acetyl-a-hexosaminidase with B-galactosidase reduced the assimilation of this enzyme by San-filippo B fibroblasts. 

One important area of current research is on the recognition of carbohydrates. In particular, cell surface carbohydrates have implications in various disease states. In some forms of cancer, closely packed cell surface carbohydrates effect cancer progression and invasiveness. Many of these carbohydrates have terminal sialic acid groups. The pinwheel receptor 42 was designed as a divalent receptor for anionic sugars including sialic acid with a view toward making sensors for cancer markers. Sensor 42 used a boronic acid to bind a diol on the... 

C,8H330,9P 584.421 Found on the asparagine-linked carbohydrate chains of lysosomal enzymes. Essential component of the enzyme recognition marker. Oil. 

It is now realized that carbohydrate moieties serve as important recognition markers on glycoproteins in solution as well as on cell surfaces. Moreover, there are examples of the role of cell surface sugars in intracellular adhesion, a key step in processes such as fertilization and cellular differentiation. 

Proteins are also covalently modified by specific enzymes that act on side-chain functional groups or on the N- or C-termini. More than 150 types of side-chain modifications are known fhese include glycosylafions, metiiy-lations, and acefylations, among otiiers. For insfance, a variety of carbohydrates are added to proteins, primarily at asparagine residues, and serve as recognition markers on cell surfaces. 

Wang, D., Liu, S., Trummer, B.J., Deng, C., and Wang, A., Carbohydrate microarrays for the recognition of cross-reactive molecular markers of microbes and host cells, Nat. Biotechnol20, 275-281, 2002. 

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