Poster Session 5, 3:15 PM - 4:00 PM: Concourse [B6]
U(GGT1) Light Up My ER: A Fluorescent Localization Study of the ER Quality Control Gatekeeper UGGT1
Presenter: Leah Grace Hoeppner
Faculty Sponsor: Lila M. Gierasch
School: UMass Amherst
Research Area: Biochemistry and Molecular Biology
ABSTRACT
The gatekeeper of protein folding in the endoplasmic reticulum (ER) is a protein known as
UGGT1. Protein folding and secretion from the ER is mediated by various N-glycan tags; these
glycans are modified by various factors to indicate the different folding and maturation states of
each client protein. UDP-glucose glycoprotein glucosyltransferase 1, or UGGT1, acts as a
checkpoint and targets misfolded proteins from being secreted by reattaching the terminal
glucose molecule to the glycan, trapping the protein in the ER for further folding assistance.
UGGT1 is highly important for proper folding; mutations have been implicated in several human
congenital diseases of glycosylation (CDGs) and mouse knockouts exhibit embryonic lethality.
Many questions remain about the recognition mechanism of this chaperone, including where
UGGT1 localizes in relation to the other factors of the ER quality control network. My research
aims to answer this question using fixed-cell immunofluorescence. This method allows for the
tagging of several proteins with fluorescent antibodies, which can then be used to calculate the
degree of colocalization between the different proteins. This will inform on where UGGT1
localizes in terms of early or late ER, as well as confirming prior localization experiments
performed in rat and Drosophila tissues. Understanding protein folding quality control is vital for
our understanding of protein folding in vivo and may help to treat misfolding in the future.
