This document summarizes a study investigating the role of the TRAPP I subunit TRS23, a guanine nucleotide exchange factor for the Ypt1/Rab GTPase, in the secretion pathway of yeast. A high copy number screen was performed on a yeast mutant with a C-terminal deletion of TRS23 (trs23Δ99C) to identify suppressors of its thermosensitive phenotype. From screening 36,000 transformed yeast colonies, 37 colonies showed suppression. Sequencing identified the gene CIN5, involved in chromosome instability, as a potential suppressor. Further experiments, such as isolating and transforming CIN5 into the trs23Δ99C mutant, are needed to confirm its role in suppress