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dc.contributor.advisorJohnson, Arthur E.en_US
dc.creatorMcCormick, Peter Josephen_US
dc.date.accessioned2005-02-17T20:58:35Z
dc.date.available2005-02-17T20:58:35Z
dc.date.created2003-12en_US
dc.date.issued2005-02-17
dc.identifier.urihttp://hdl.handle.net/1969.1/1304
dc.description.abstractDuring co-translational integration, the transmembrane (TM) sequence of a nascent membrane protein moves laterally into the ER lipid bilayer upon reaching the translocon. Our lab has previously shown that this movement is a multistep process, but it was not clear whether the observed photocrosslinking of the TM segment to translocon proteins resulted from specific interactions or simply from TM-translocon proximity. If the latter, the TM α-helix will be oriented randomly with respect to translocon proteins, whereas, if the former, a specific TM helix surface would face TRAM and/or Sec61α. Integration intermediates were prepared by in vitro translation of truncated mRNAs in the presence of a Lys-tRNA analog with a photoreactive moiety attached to the lysine side-chain. When photoadduct formation was monitored as a function of probe location within the TM α-helix, we found that the extent of photocrosslinking to TRAM and Sec61α was non-random. Thus, the TM sequence occupies a distinct location within the translocon, a result that can only be achieved through protein-protein interactions that mediate the lateral movement, positioning, and integration of the TM sequence. In the case of multi-spanning membrane proteins, it was unknown how multiple hydrophobic regions integrated into the ER membrane. By placing photoprobes within each of several TM domains of a multi-spanning membrane protein, we were able to determine at what stage of integration each TM segment was no longer adjacent to translocon proteins. Using this approach we were able to establish a mechanism of integration for multi-spanning membrane proteins co-translationally inserted into the ER membrane.en_US
dc.format.extent1822779 bytes
dc.format.mediumelectronicen_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherTexas A&M Universityen_US
dc.subjectProtein Traffickingen_US
dc.subjectMembrane Proteinen_US
dc.subjectIntegrationen_US
dc.subjectERen_US
dc.titleInvestigating cotranslational protein integration into the endoplasmic reticulum membraneen_US
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentBiochemistry and Biophysicsen_US
thesis.degree.disciplineBiochemistryen_US
thesis.degree.grantorTexas A&M Universityen_US
thesis.degree.nameDoctor of Philosophyen_US
thesis.degree.levelDoctoralen_US
dc.contributor.committeeMemberReinhart, Gregoryen_US
dc.contributor.committeeMemberScholtz, John M.en_US
dc.contributor.committeeMemberKladde, Michaelen_US
dc.type.genreElectronic Dissertationen_US
dc.type.materialtexten_US
dc.format.digitalOriginborn digitalen_US


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