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Dissertation/Thesis Abstract

A Study of Vacuolar Kinase Env7 Trafficking in Saccharomyces cerevisiae
by Frisardi, Leah, M.S., California State University, Long Beach, 2019, 65; 13859804
Abstract (Summary)

The vacuole in Saccharomyces cerevisiae (baker’s yeast) is functionally analogous to the human lysosome. Endosome and vacuolar interface 7 (Env7) has been recently identified in the Gharakhanian laboratory as a protein kinase that regulates vacuolar fusion and has a human ortholog, STK16. Previous research in our laboratory has shown that Env7 localizes to the vacuolar membrane in yeast. Proteins destined to function at the yeast vacuole are transported from the Golgi via two distinct pathways: the carboxypeptidase Y (CPY) pathway and the alkaline phosphatase (ALP) pathway. The CPY pathway requires an endosomal intermediate while the ALP pathway requires an adaptor protein complex (AP-3). The CPY pathway serves as the default pathway for the vast majority of proteins moving from the Golgi to the vacuole. Only 9 proteins are known to be transported via the ALP pathway in yeast, all of which are vacuolar membrane proteins and one of which is Yck3, a palmitoylated protein kinase with a similar function of Env7. Proteins normally transported to the yeast vacuole via the ALP pathway are able to partially revert to the CPY pathway when AP-3 function is disrupted. In the absence of a functional CPY pathway, however, the AP-3 pathway remains cargo-specific. Here we show that when the CPY pathway is disrupted in yeast cells, Env7 shows a significant increase in mislocalization. When the ALP pathway is disrupted, Env7 shows no significant mislocalization. Proteins transported via the ALP pathway interact with AP-3 via either an acidic-dileucine-like or a tyrosine-based adaptin sorting signal. Analysis of the amino acid sequence of Env7 showed one potential acidic-dileucine like signal and four potential tyrosine-based adaptin sorting signals. Mutagenesis of two of these sorting signals caused no significant mislocalization of Env7 in yeast. These results implicate the CPY pathway in the vacuolar trafficking of Env7 in yeast.

Indexing (document details)
Advisor: Gharakhanian, Editte
Commitee: Fraser, Deborah, Brusslan, Judith
School: California State University, Long Beach
Department: Biological Sciences
School Location: United States -- California
Source: MAI 81/1(E), Masters Abstracts International
Subjects: Molecular biology
Publication Number: 13859804
ISBN: 9781085558846
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