Core glycosylation

Upper panel The hydropathy profile of the entire 69 kD precursor protein is shown. The abscissa is amino acid residues and the ordinate, positive values indicate hydrophilic. The black and hatched rectangles at the bottom of the figure denote the calculated signal sequence and amino-terminal propeptide domains, respectively. The mature and carboxyl-terminal domains are labeled. N-linked core glycosylation consensus sites are depicted by branched structures. 

GAA is synthesized as a 110 kDa precursor protein, which is core-glycosylated in the ER and acquires mannose 6-phosphate (M6P) residues in the Golgi as diagrammed in Fig. 10.1. In the lysosomal compartments, the precursor protein is processed to yield an intermediate 95 kDa form and the two mature, fully active, 76 and 70 kDa, forms of GAA (Reuser et al., 1995 Raben et al., 2002). The 110 kDa form is secreted and can be detected in the media of infected cells or serum of transduced animals and the remaining forms can be found in expressing cells. 

Once the secondary fatty acyl residue(s), VLCFA, has been added to the Kd02lipid-IVA, a number of the core glycosyl residues are added and then, presumably, the resulting COS-LA molecule is flipped to the periplasmic side of the inner membrane after which the OPS is ligated to the COS-LA which is then translocated to the outer leaflet of the outer membrane. The enzymes which modify the... 

Kanjilal-Kolar, S., Raetz, C.R.H. Dodecaprenyl phosphate-galacturonic acid as a donor substrate for lipopolysaccharide core glycosylation in Rhizobium leguminosarum. J Biol Chem 281... 

Bernstein, M., Kepes, F., and Schekman, R. (1989). Sec59 encodes a membrane protein required for core glycosylation in Saccharomyces cerevisiae. Mol. Cell Biol. 9,1191—1199. 

Fig. 4 The glycosylation pathway via ER and Golgi apparatus. In the cytosol carbohydrates are attached to a lipid precursor, which is then transported into the lumen of the ER to finish core glycosylation. This glycan is now attached to the nascent, folding polypeptide chain (which is synthesized by ribosomes attached to the...

Core glycosylation of newly synthesized rat a-lactalbumin occurs in vitro in a microsomal membrane supplemented system. Processing, segregation, and core glycosylation were observed only when membranes were present during translation and not when they were added after translation. 

Shakin-Eshleman, S. H., Spitalnik, S. L. and Kasturi, L. The amino acid at the X position of an Asn-X-ser sequon is an important determinant of N-linked core-glycosylation efficiency.. Biol. Chem. 271 6356-6363, 1996. 

Bonatti, S., Cancedda, R., and Blobel, G., 1979, Membrane biogenesis In vitro cleavage, core glycosylation and integration into microsomal membranes of Sindbis virus glycoproteins, J. Cell. Biol. 80 219. 

J.L. Kadrmas, K.A. Brozek, and C.R.H. Raetz, Lipopolysaccharide core glycosylation in Rhizohium leguminosarum. An unusual Man-T resembling the heptosyltransferase I of Escherichia coli, J. Biol Chem. 1996, 271, 32119-32125. 

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