The transport of Ca2+across membranes precedes the fusion and fission of various lipid bilayers. Yeast vacuoles under hyperosmotic stress become fragmented through fission events that requires the release of Ca2+stores through the TRP channel Yvc1. This requires the phosphorylation of phosphatidylinositol‐3‐phosphate (PI3P) by the PI3P‐5‐kinase Fab1 to produce transient PI(3,5)P2pools. Ca2+is also released during vacuole fusion upon
Phosphatidylinositol (PI) is an essential phospholipid, critical to membrane bilayers. The complete deacylation of PI by B‐type phospholipases produces intracellular and extracellular glycerophosphoinositol (GPI). Extracellular GPI is transported into the cell via Git1, a member of the Major Facilitator Superfamily of transporters at the yeast plasma membrane. Internalized GPI is degraded to produce inositol, phosphate and glycerol, thereby contributing to these pools.
We find that the α‐arrestins, an important class of protein trafficking adaptor, regulate Git1 localization and this is dependent upon their interaction with the ubiquitin ligase Rsp5. Specifically, α‐arrestin Aly2 stimulates Git1 trafficking to the vacuole under basal conditions, but in response to GPI‐treatment, either Aly1 or Aly2 promote Git1 vacuole trafficking. Cell surface retention of Git1, as occurs in
The α‐arrestins Aly1 and Aly2 are novel regulators of Git1 trafficking with previously unanticipated roles in controlling phospholipid distribution and balance.
To our knowledge, this is the first example of α‐arrestin regulation of phosphatidyliniositol‐3‐phosphate levels. In future studies it will be exciting to determine if other α‐arrestins similarly alter PI and PIPs to change the cellular landscape.
- NSF-PAR ID:
- 10445081
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Biology of the Cell
- Volume:
- 114
- Issue:
- 1
- ISSN:
- 0248-4900
- Page Range / eLocation ID:
- p. 3-31
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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