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Molecular & Cellular Biology
Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
Dynein Pathway, Mitosis, Saccharomyces cerevisiae, BiMolecular Fluorescence Complementation, Lis1/Pac1 Bik1/Clip-170
Dynein is a minus end directed molecular motor required for numerous cellular processes during intracellular transport and mitosis. Pac1/LIS1 and Bik1/CLIP-170 are two proteins required for targeting dynein to cytoplasmic microtubule plus ends in budding yeast. The lab previously proposed a model whereby Pac1/LIS1 binds to the motor domain of dynein heavy chain, Dyn1/HC, forming a complex that interacts with the +TIP protein Bik1/CLIP170 at plus ends. This project focused on using Bimolecular Fluorescence Complementation (BiFC) to visualize protein-protein interactions among dynein pathway components in vivo. Budding yeast, Saccharomyces cerevisiae is an ideal system to manipulate dynein as it is a non-essential protein in this system.
The BiFC assay fuses two non-fluorescent halves of Venus, a YFP-derivative, to proteins of interest. If an interaction between the proteins occur, the two halves are brought to close proximity and the fluorophore is reconstituted.
Cells co-expressing Dyn1-VN with Pac1-VC or Bik1-VC exhibited fluorescent foci associated with microtubule plus ends, the cell cortex and spindle pole bodies (SPBs). Additionally, cells co-expressing Pac1-VC with Bik1-VN exhibited fluorescent foci associated with microtubule plus ends.
Cells coexpressing Tub1-VC and Bik1-VN or Dyn1-VN have BiFC signal indicating that both interact with the microtubule directly. Pac-1 coexpressed with Tub1 had no signal above background. These data support that these three components associate at microtubule plus ends. Dyn1 and Pac1 interact with Bik1 at microtubule plus ends. Bik1 serves as a docking platform for the two, but dynein is still able to interact with microtubules, while Pac1 is not.