Ypts and TRAPPs in Golgi Dynamics
thesisposted on 2016-10-19, 00:00 authored by Jane J. Kim
The conserved Ypt/Rab GTPases regulate the pathways of intracellular transport in eukaryotic cells. They accomplish this regulation in conjunction with their activators, guanine exchange factors (GEFs). Yeast Ypt1 (mammalian Rab1) and Ypt31/32 (mammalian Rab11) are essential for ER-to-Golgi and Golgi-to-PM trafficking, respectively. However, regulation of intra-Golgi processes, such as Golgi cisternal progression, by these Ypt/Rabs remains poorly understood. In this thesis, I report findings on Ypt1 and Ypt31 as well as their GEFs, the TRAPPI and TRAPPII complexes, within the Golgi. Using live-cell microscopy and immunofluorescence, I establish that Ypt1 and Ypt31 polarize to opposite ends of the Golgi, early and late, respectively. They co-localize on a compartment that contains both early and late Golgi proteins, which I termed transitional. Furthermore, using live-cell and time-lapse microscopy, I show that Ypt1 and Ypt31 regulate two distinct Golgi cisternal progression steps, early-to-transitional and transitional-to-late, respectively. Correspondingly, I provide evidence that the TRAPPII complex has a similar pattern of Golgi compartmental localization as Ypt31 and not of Ypt1. Together, these results show novel regulation for Golgi cisternal maturation by Ypt/Rab GTPases, clears up controversy for the placement of Ypt1 and Ypt31 to specific Golgi compartments, and places TRAPPII as the GEF for Ypt31 in vivo.
Degree GrantorUniversity of Illinois at Chicago
Committee MemberShikano, Sojin Glick, Ben Alford, Simon Stone, Dave Segev, Nava