# Dissecting the functions of yeast COPI

> **NIH NIH R01** · UNIVERSITY OF CHICAGO · 2020 · $437,901

## Abstract

Membrane traffic researchers have an increasingly detailed view of the mechanisms that drive vesicular
transport, but we have only a limited grasp of the events that create, maintain, and transform membrane
compartments. Based partly on work from my group, budding yeasts are a powerful system for tackling
these questions. We will employ the yeasts Saccharomyces cerevisiae and Pichia pastoris to explore
fundamental aspects of membrane compartmentation and organization.
 Specific Aim #1 is to characterize how cisternal maturation drives secretory cargo
transport and Golgi compartmentation using S. cerevisiae. The nonstacked Golgi in S. cerevisiae
enables the maturation of individual cisternae to be visualized by fluorescence microscopy. We will use
this system to test the assumption that secretory cargo proteins travel through the Golgi in maturing
cisternae, and to address the long-standing question of how Golgi cisternae become functionally
specialized. Sub-Aim #1A is to track a fluorescent secretory cargo through the Golgi during cisternal
maturation. Our hypothesis is that secretory cargo proteins remain in maturing cisternae as resident Golgi
proteins come and go. We will test this hypothesis using a novel regulatable fluorescent secretory cargo
that can be trapped in the yeast ER and then released for transport through the Golgi. Sub-Aim #1B is to
define Golgi organization by a kinetic analysis of resident Golgi proteins. Our hypothesis is that Golgi
maturation occurs in discrete kinetic stages that generate functionally distinct types of cisternae. To test
this idea and to classify Golgi cisternae, we will perform a systematic, quantitative study of the relative
arrival and departure times of resident S. cerevisiae Golgi proteins in wild-type and mutant strains.
 Specific Aim #2 is to characterize the physical and functional interactions of ER exit sites
(ERES) with other compartments using P. pastoris. A typical P. pastoris cell has 3-4 ERES, each of
which is next to a Golgi stack. We will explore the relationship of the ERES with the early Golgi and with
the pre-autophagosomal structure (PAS). Sub-Aim #2A is to test whether ERES formation requires
association with the early Golgi. Our hypothesis is that the unit of self-organization in the early secretory
pathway consists of an ERES plus associated early Golgi membranes. To test this idea, we will seek to
disrupt the tethers that link the ERES to the early Golgi in P. pastoris, and will determine whether ERES
organization is lost in the absence of tethering. Sub-Aim #2B is to test whether PAS assembly occurs in
proximity to functionally specialized ERES. Our hypothesis is that specialized ERES in P. pastoris
associate with both the vacuole and the PAS. We will take advantage of the simple morphology in this
yeast to clarify how the location and dynamics of the PAS relate to those of ERES.

## Key facts

- **NIH application ID:** 9957153
- **Project number:** 5R01GM104010-08
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** BENJAMIN S GLICK
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $437,901
- **Award type:** 5
- **Project period:** 2013-09-15 → 2021-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9957153

## Citation

> US National Institutes of Health, RePORTER application 9957153, Dissecting the functions of yeast COPI (5R01GM104010-08). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/9957153. Licensed CC0.

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