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The Characterization of Baxb, a Splice Variant of the Pro-Apoptotic Bax and Protein

Baxa is a pro-apoptotic member of the Bcl-2 protein family that regulates a
key point in the control of apoptosis. The bax RNA undergoes a complex pattern
of RNA splicing, with eight splice isoforms known to date. The next most
abundant isoform to Baxa is Baxp, which has a unique carboxyl-terminal
sequence and consequently lacks the transmembrane domain of Baxa. This
study characterized Baxp as part of a larger project aimed at deducing the role of
cellular localization in Bax protein function.
A transient transfection assay was designed to determine the cell death
activity of a protein in adherent cells. Baxp induced cell death to a greater extent
than Baxa when transiently expressed in NIH 3T3 cells. The levels of Baxp
expression were always low, regardless of the cell type or transfection method
used. Additionally, Baxp adopted a conformation in which amino acids 13 to 19
are accessible to the monoclonal antibody 6A7. In Baxa this epitope is only
exposed in the membrane-bound activated conformation that is associated with
accessibility of the BH3 domain of Baxa that mediates protein-protein
interactions among Bcl-2 family members. Although the mechanism remains
elusive, Baxp was identified as a potent inducer of cell death. / Thesis / Master of Science (MSc)

Identiferoai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22650
Date12 1900
CreatorsPound, Kathleen
ContributorsAndrews, D.W, Biochemistry
Source SetsMcMaster University
Languageen_US
Detected LanguageEnglish
TypeThesis

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