Deciphering the "Polarity Code": the Mechanism of Par Complex Substrate Polarization

Simple item page
dc.contributor.advisorPrehoda, Kenneth
dc.contributor.authorBailey, Matthew
dc.date.accessioned2017-09-27T21:43:43Z
dc.date.issued2017-09-27
dc.description.abstractAnimal cells, as distinct as epithelia and migratory cells, have cell polarity that is defined by a common set of molecules. The Par complex polarizes the cortex of animal cells through the activity of atypical protein kinase C (aPKC). In this work, I aimed to determine the mechanism of aPKC substrate polarization and identify common characteristics of aPKC substrates that are polarized by phosphorylation. I found that several diverse Par-polarized proteins contain short highly basic and hydrophobic motifs that overlap with their aPKC phosphorylation sites. These Phospho-Regulated Basic and Hydrophobic (PRBH) motifs mediate plasma membrane localization by electrostatics-based phospholipid binding when unphosphorylated but are displaced into the cytoplasm when phosphorylated. To assess whether the Par complex polarizes other proteins by this mechanism, I developed an algorithm to identify potential PRBH motifs and score these linear motifs for basic and hydrophobic character, as well as the quality and number of aPKC phosphorylation sites. Using this algorithm, I identified numerous putative PRBH candidates in the fruit fly proteome and performed two screens of these candidates for Par-polarized proteins. The first screen focused on determining whether aPKC regulates cortical targeting of proteins that are reported to be polarized. This screen identified the Rho GAP crossveinless-c (cv-c) to be a novel aPKC substrate and found that aPKC is sufficient to polarize cv-c in a reconstituted polarity assay. The second screen characterized the localization of putative PRBH motif-containing proteins in vivo. This screen identified a previously uncharacterized protein, CG6454, to be basolateral in epithelia; however, ex vivo experiments found it to have a Ca2+-dependent and aPKC-independent membrane targeting mechanism. Overall this work identified a common mechanism for Par substrate polarization and used knowledge of this mechanism to identify a novel Par effector. This dissertation contains previously published coauthored materials as well as unpublished materials.en_US
dc.description.embargo2019-05-08
dc.identifier.urihttps://hdl.handle.net/1794/22782
dc.language.isoen_US
dc.publisherUniversity of Oregon
dc.rightsAll Rights Reserved.
dc.subjectAsymmetric cell divisionen_US
dc.subjectAtypical Protein Kinase Cen_US
dc.subjectCell polarityen_US
dc.subjectPar complexen_US
dc.titleDeciphering the "Polarity Code": the Mechanism of Par Complex Substrate Polarization
dc.typeElectronic Thesis or Dissertation
thesis.degree.disciplineDepartment of Chemistry and Biochemistry
thesis.degree.grantorUniversity of Oregon
thesis.degree.leveldoctoral
thesis.degree.namePh.D.

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Bailey_oregon_0171A_11782.pdf
Size:
52.97 MB
Format:
Adobe Portable Document Format
Download

Collections

Theses and Dissertations
Chemistry Theses and Dissertations