Masters Theses

Date of Award

5-1997

Degree Type

Thesis

Degree Name

Master of Science

Major

Life Sciences

Major Professor

Jeffrey M. Becker

Committee Members

W.S. Riggsy, Robert N. Moore, Cynthia B. Peterson

Abstract

Mating in Saccharomyces cerevisiae is initiated by extracellular peptides, known as mating pheromones. The mating factors are recognized by membrane-bound receptors which are similar to receptors in mammalian cells. The pheromone system of the S. cerevisiae can be used as a model to understand the mode of action of peptide hormones in more complex mammalian systems. The purpose of this thesis is to provide information regarding the yeast lipopeptide pheromone, a-factor. The first part of this project, described in Chapter 2, was the development of an assay which could be used to define the binding of a-factor to its receptor. The assay, which made use of membrane preparations in place of whole cells, was able to show that a larger percentage of the radioactive a-factor pheromone did bind to membranes which contained the a-factor receptor (Ste3p) when compared to membranes which lacked the receptor. However, further experiments are needed to more clearly define the pheromone/receptor interaction. The second part of this project, described in Chapter 3, was the examination of the role of the farnesyl group in a-factor bioactivity, particularly mating restoration. This examination made use of a-factors with altered farnesyl groups that contained the novel lipid substitutions of the 3-methyl moiety with bulkier additions. The study suggested that there is a specific preference for a particular relationship between the membrane and the ligand with regard to bioactivity, and that this preference is mediated via the farnesyl group. Thus, the farnesyl group may also play a role in presentation of the peptide portion to the receptor in addition to its role in membrane localization.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS