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Macromolecular Complexes Regulate Non‐Vesicular Phosphatidylserine Traffic in Yeast
Author(s) -
Riekhof Wayne R,
Voelker Dennis R
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a83-a
Subject(s) - golgi apparatus , golgi membrane , phosphatidylserine , microbiology and biotechnology , transport protein , organelle , biology , membrane protein , integral membrane protein , chemistry , biochemistry , endoplasmic reticulum , membrane , phospholipid
Phosphatidylserine (PtdSer) transport to the loci of PtdSer decarboxylases 1 and 2 (Psd1p and Psd2p) in the mitochondria and Golgi, has previously been used as a genetic and biochemical tool to identify molecules involved in lipid traffic. Three genes ( STT4 , PSTB2 and PSD2 ) have been implicated in regulation of PtdSer transport to Psd2p. These genes encode a PtdIns‐4‐kinase (Stt4p), a lipid binding protein (PstB2p) and Psd2p itself. Using the split ubiquitin system for analysis of membrane protein interactions we examined whether stable complexes were formed among these proteins and others. Prior analyses defined a biochemical and genetic requirement for the presence of PstB2p and a C2 domain of Psd2p on the Golgi for PtdSer transport. We now show that PstB2p forms a stable complex with Psd2p through two C2 domains present on the enzyme. In addition, PstB2p binds a second protein named Pbi1p. The Pbi1p also interacts with an integral ER membrane tethering protein named Scs2p. Independently of our work, Scs2p has previously been shown to co‐localize to protein complexes containing Stt4p. These findings identify a network of protein‐protein interactions with the characteristics expected for docking the ER to the Golgi and assembling a macromolecular complex that facilitates and regulates the movement of PtdSer between the organelles.