Faculty Mentor(s)

Dr. Leah Chase, Biology and Chemistry

Document Type


Event Date



xCT plays a role in protecting cells from oxidative stress as well as intracellular glutathione synthesis. If this process is impeded, reactive oxygen species accumulate in the cell, leading to cellular damage, and if left unchecked, it can lead to neuronal loss. Ubiquitin is a small protein that some evidence suggests can negatively affect the stress response pathway modulated by xCT, as well as induce cell death. It is hypothesized that ubiquitin binds to xCT on the N-terminal lysine residues, and there are six conserved lysines in the N-terminal domain at positions K4R, K12R, K30R, K37R, K41R, and K43R. Previous work in the Chase lab has shown that the replacement of individual lysines with arginines does not result in a change in the ubiquitination of a transporter. Therefore, the goal of this project is to create a mutant of xCT in which all of the lysines in the N-terminus are replaced with arginines in order to determine if that will lead to a loss of ubiquitination of xCT and an overall change in the activity and regulation of the transporter. To do this, we did a successive site-directed mutagenesis approach to ultimately produce a mutant with all lysines replaced with arginines. Currently, we have created a construct that has mutations at K4R, K37R, K41R, and K43R, and we are attempting to add the final mutations. Once this is accomplished we will express it in COS7 cells, and determine if the mutant can still be ubiquitinated.


This research was supported by the A. Paul and Carol Schaap Undergraduate Research Fund.