Persistent Link:
http://hdl.handle.net/10150/279787
Title:
Lipoprotein biosynthesis: Examination of the lipidation process
Author:
Karnas, Kimberly Joy
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Lipoproteins, protein-lipid complexes that have a polar exterior and a non-polar interior, have been found in many vertebrate and insect species, and their basic structure and function appear to be conserved. They facilitate the intercellular transport of hydrophobic lipids through aqueous media. Their synthesis requires an unusual process referred to as lipidation, whereby lipids are added to the protein component of the lipoprotein. Lipidation is thought to occur during or immediately following translation of these proteins, but how this process occurs is unknown. Of particular interest is the extent to which the protein sequence of the apoproteins drives lipidation and the level of involvement of other proteins in this process. In this project, lipidation was studied by expressing the apolipoproteins from the tobacco hornworm, Manduca sexta, in two different expression systems. The first used budding yeast, Saccharomyces cerevisiae , to both determine the ability of unicellular organisms to produce lipoproteins and examine the role that the known secretory pathway for soluble proteins plays in lipoprotein biosynthesis. The second used Drosophila Schneider 2 cells to begin to examine the apolipoprotein sequence for regions that are crucial to lipoprotein biosynthesis. The yeast expression system revealed that unicellular organisms are capable of expressing, lipidating, and secreting M. sexta apolipoproteins. This is first demonstration of any apolipoprotein being expressed in a unicellular organism, and represents a major finding, as unicellular organisms have no need for a particle that functions in intercellular transport. A second major finding in this project is that lipophorin production occurs in the absence of the full apoLp-I sequence. This finding was true for both expression systems, and indicates that the lipidation code resides within the first 45% of the precursor protein sequence. Furthermore, deletion analysis has revealed that removal of any portion of the apoLp-II sequence prevents expression of the apolipoprotein. Taken together, these experiments indicate that all of the information required to make a lipoprotein is included in the apoLp-II sequence.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Molecular.; Biology, Entomology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Molecular and Cellular Biology
Degree Grantor:
University of Arizona
Advisor:
Wells, Michael A.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleLipoprotein biosynthesis: Examination of the lipidation processen_US
dc.creatorKarnas, Kimberly Joyen_US
dc.contributor.authorKarnas, Kimberly Joyen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractLipoproteins, protein-lipid complexes that have a polar exterior and a non-polar interior, have been found in many vertebrate and insect species, and their basic structure and function appear to be conserved. They facilitate the intercellular transport of hydrophobic lipids through aqueous media. Their synthesis requires an unusual process referred to as lipidation, whereby lipids are added to the protein component of the lipoprotein. Lipidation is thought to occur during or immediately following translation of these proteins, but how this process occurs is unknown. Of particular interest is the extent to which the protein sequence of the apoproteins drives lipidation and the level of involvement of other proteins in this process. In this project, lipidation was studied by expressing the apolipoproteins from the tobacco hornworm, Manduca sexta, in two different expression systems. The first used budding yeast, Saccharomyces cerevisiae , to both determine the ability of unicellular organisms to produce lipoproteins and examine the role that the known secretory pathway for soluble proteins plays in lipoprotein biosynthesis. The second used Drosophila Schneider 2 cells to begin to examine the apolipoprotein sequence for regions that are crucial to lipoprotein biosynthesis. The yeast expression system revealed that unicellular organisms are capable of expressing, lipidating, and secreting M. sexta apolipoproteins. This is first demonstration of any apolipoprotein being expressed in a unicellular organism, and represents a major finding, as unicellular organisms have no need for a particle that functions in intercellular transport. A second major finding in this project is that lipophorin production occurs in the absence of the full apoLp-I sequence. This finding was true for both expression systems, and indicates that the lipidation code resides within the first 45% of the precursor protein sequence. Furthermore, deletion analysis has revealed that removal of any portion of the apoLp-II sequence prevents expression of the apolipoprotein. Taken together, these experiments indicate that all of the information required to make a lipoprotein is included in the apoLp-II sequence.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Molecular.en_US
dc.subjectBiology, Entomology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineMolecular and Cellular Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWells, Michael A.en_US
dc.identifier.proquest3016493en_US
dc.identifier.bibrecord.b41939141en_US
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