Biosynthesis of intestinal microvillar proteins. Further characterization of the intracellular processing and transport
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Biosynthesis of intestinal microvillar proteins. Further characterization of the intracellular processing and transport. / Danielsen, E M; Cowell, G M.
I: FEBS Letters, Bind 166, Nr. 1, 1984, s. 28-32.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Biosynthesis of intestinal microvillar proteins. Further characterization of the intracellular processing and transport
AU - Danielsen, E M
AU - Cowell, G M
N1 - Keywords: Aminopeptidases; Animals; Biological Transport; Glucosamine; Glucosidases; Glycoproteins; Intestinal Mucosa; Leupeptins; Microvilli; Molecular Weight; Multienzyme Complexes; Sucrase-Isomaltase Complex; Swine; Tunicamycin; alpha-Glucosidases
PY - 1984
Y1 - 1984
N2 - 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.
AB - 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.
M3 - Journal article
C2 - 6363129
VL - 166
SP - 28
EP - 32
JO - F E B S Letters
JF - F E B S Letters
SN - 0014-5793
IS - 1
ER -
ID: 9881401