Najjar SM, Broyart JP, Hampp LT, Gray GM. Sucrase-alpha-dextrinase in the spontaneously diabetic BioBreed Wistar rat: altered intracellular carbohydrate processing.
J Cell Biochem 2001;
81:252-61. [PMID:
11241665 DOI:
10.1002/1097-4644(20010501)81:2<252::aid-jcb1040>3.0.co;2-x]
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Abstract
Sucrase-alpha-dextrinase (S-D), a glycoprotein hydrolase in the border surface of the enterocyte, is altered in congenitally diabetic BioBreed Wistar (BB(d)) rats. Its intracellular assembly was examined in the current studies. Following pulse-chase experiments, S--D was specifically immuno-isolated from ER-Golgi and brush border membranes, and examined by SDS-PAGE and autoradiography. While synthesis and co-translational glycosylation of an immature species, P(i), in the ER proceeded normally, post-translational maturation of the N-linked carbohydrate chains was altered in the BB(d) rat. The mature species, P(m), was 10 kDa larger in BB(d) than in normal rats, and approximately 25% of its N-linked chains remained immature. The difference in mass was attributed to an appreciably larger mass of the O-linked chains of P(m) in BB(d) rats. In vivo kinetics of intracellular assembly displayed a delay in the appearance of P(m) in Golgi (Wistar, 15 min; BB(d), 30--60 min). These experiments, revealing structural alterations in congenital diabetes suggest an important role for intracellular glycosylation in the orderly assembly and processing of brush border S-D in the enterocyte.
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