Biosynthesis of intestinal microvillar proteins

FEBS Letters

Cowell, Gillian M.¹  Danielsen, E.Michael¹ 

[1] Department of Biochemistry C, Panum Institute, University of Copenhagen, 3 Blegdamsvej, DK-2200 Copenhagen, Denmark

关键词: Microvillar enzyme;    Biogenesis;    Processing;    Organ culture;    Tunicamycin;    Endo F;   

DOI  :  10.1016/0014-5793(84)80038-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The effect of tunicamycin on synthesis and intracellular transport of pig small intestinal aminopeptidase N (EC 3.4.11.2), sucrase-isomaltase (EC 3.2.1.48–10) and maltase-glucoamylase (EC 3.2.1.20) was studied by labelling of mucosal explants with [³⁵S]methionine. The expression of the microvillar enzymes was greatly reduced by tunicamycin but could be partially restored by leupeptin, suggesting the existence of a mechanism whereby newly synthesized, malprocessed enzymes are recognized and degraded. In the presence of tunicamycin, polypeptides likely to represent non-glycosylated forms of the enzymes persisted in the Mg²⁺-precipitated membrane fraction, indicating that high mannose glycosylation is essential for transport to the microvillar membrane. Treatment of aminopeptidase N and sucrase-isomaltase with endo F reduced the size of the high mannose forms approximately to those seen in the presence of tunicamycin. The complex forms were also sensitive to endo F but did not coincide with the high mannose forms after treatment, indicating that the size difference cannot alone be ascribed to processing of N-linked carbohydrate.

【 授权许可】

Unknown