title: Biosynthetic route of locust apolipophorin III isoforms.
abstract: Insect apolipophorin III (apoLp-III) plays a key role in the enhanced diacylglycerol transport during insect flight. For apoLp-III of the migratory locust, two different isoforms have been described (apoLp-IIIa and -b), displaying different N-termini and isoelectric points; each of the isoforms is however equally well capable to perform its function in lipid transport. In the present report the biosynthetic route of the apoLp-III isoforms is elucidated. Immunoprecipitation of media from in vitro fat body incubations and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the locust fat body synthesized and secreted apoLp-III. ApoLp-III levels in the hemolymph showed that in young adults, apoLp-III concentrations were only very low (1-3 mg/ml). During adult maturation, however, the apoLp-III concentration increased rapidly to approximately 17 mg/ml. During apoLp-III elevation, the apoLp-IIIa:-b ratio remained equal or in the favour of the a-isoform, while in adults from approximately 12 days after adult ecdysis apoLp-IIIb was the most abundant isoform. Analysis of the protein by native polyacrylamide gel electrophoresis showed that only the apoLp-IIIa form was secreted. Injection of radiolabeled apoLp-IIIa into the hemolymph of adult locusts resulted in a slow conversion into apoLp-IIIb.
authors.affiliation: Department of Experimental Zoology, University of Utrecht.
authors.forename: P M
authors.initials: PM
authors.lastname: Weers
authors.forename: J
authors.initials: J
authors.lastname: Van Baal
authors.forename: J M
authors.initials: JM
authors.lastname: Van Doorn
authors.forename: R
authors.initials: R
authors.lastname: Ziegler
authors.forename: D J
authors.initials: DJ
authors.lastname: Van der Horst
mesh_terms: D000818:Animals; D001053:Apolipoproteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005216:Fat Body / Q000378:metabolism*; D006110:Grasshoppers / Q000254:growth & development / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism; D066298:In Vitro Techniques; D008970:Molecular Weight; D011233:Precipitin Tests
chemical_list: D001053:Apolipoproteins; D002352:Carrier Proteins; C042470:apolipophorin III