Biosynthesis of locust lipophorin: apolipophorins I and II originate from a common precursor

Biosynthesis of apolipophorins of high density lipophorin of the locust Locusta migratoria was studied in vitro. Analysis of immunoprecipitates from homogenates of in vitro labeled fat body revealed a common precursor for apolipophorin I (apoLp-I, Mr 220,000) and apolipophorin II (apoLp-II, Mr 72,00...

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Bibliographic Details
Published in:The Journal of biological chemistry 1993-02, Vol.268 (6), p.4300-4303
Main Authors: Weers, P.M.M. (University of Utrecht, Utrecht, The Netherlands), Marrewijk, W.J.A. van, Beenakkers, A.M.T, Horst, D.J. van der
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Animals
Apolipoproteins - biosynthesis
Apolipoproteins - metabolism
APPAREIL DIGESTIF
Biological and medical sciences
Carrier Proteins - biosynthesis
Carrier Proteins - metabolism
forms
Fundamental and applied biological sciences. Psychology
Glycosylation
Grasshoppers - metabolism
Lipid Metabolism
LIPIDE
LIPIDOS
lipophorin
LIPOPROTEINAS
LIPOPROTEINE
Lipoproteins
Lipoproteins, myelin
LOCUSTA MIGRATORIA
Male
protein biosynthesis
Protein Precursors - metabolism
PROTEINAS
PROTEINE
Proteins
SECRECION
SECRETION
SINTESIS DE PROTEINAS
SISTEMA DIGESTIVO
SYNTHESE PROTEIQUE
synthesis
Tunicamycin - pharmacology
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Summary:Biosynthesis of apolipophorins of high density lipophorin of the locust Locusta migratoria was studied in vitro. Analysis of immunoprecipitates from homogenates of in vitro labeled fat body revealed a common precursor for apolipophorin I (apoLp-I, Mr 220,000) and apolipophorin II (apoLp-II, Mr 72,000) with a molecular mass of approximately 280 kDa. Pulse-chase experiments showed that this high molecular mass precursor is cleaved into apoLp-I and apoLp-II which subsequently are secreted as high density lipophorin from the fat body. The time required for the complete synthesis and secretion was estimated to be approximately 35 min. Both apolipophorins are glycoproteins as demonstrated by the incorporation of [3H] mannose. Treatment of [3H]mannose-labeled apolipophorin with endoglycosidase H resulted in the complete removal of the incorporated [3H]mannose. Endoglycosidase H treatment [3H]leucine-labeled apolipophorins caused a reduction in molecular mass of approximately 3 kDa for apoLp-I and 3.5 kDa for apoLp-II, suggesting the N-linked carbohydrate content to be 1-2 and 5%, respectively. Incubation of fat body tissue in the presence of low concentrations of tunicamycin led to the synthesis and release of nonglycosylated apolipophorins
ISSN:0021-9258
1083-351X
DOI:10.1016/s0021-9258(18)53609-7