Secretion of the mammalian Sec14p‐like phosphoinositide‐binding p45 protein

Protein–lipid interactions are important for protein targeting, signal transduction, lipid transport, and the maintenance of cellular compartments and membranes. Specific lipid‐binding protein domains, such as PH, FYVE, PX, PHD, C2 and SEC14 homology domains, mediate interactions between proteins an...

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Published in:The FEBS journal 2005-11, Vol.272 (21), p.5595-5605
Main Authors: Merkulova, Maria, Huynh, Huong, Radchenko, Vitaly, Saito, Kan, Lipkin, Valery, Shuvaeva, Tatiana, Mustelin, Tomas
Format: Article
Language:English
Subjects:
Animals
Biochemistry
Carboxypeptidase H - metabolism
Carrier Proteins - chemistry
Carrier Proteins - metabolism
Carrier Proteins - secretion
Cells
CRAL/TRIO domain
GOLD domain
Lipids
Mammals
Molecular Weight
nonclassical protein secretion
Phosphatidylinositols - metabolism
phosphoinositides
Phospholipid Transfer Proteins - chemistry
Proteins
Rats
Saccharomyces cerevisiae Proteins - chemistry
Sec14p
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Summary:Protein–lipid interactions are important for protein targeting, signal transduction, lipid transport, and the maintenance of cellular compartments and membranes. Specific lipid‐binding protein domains, such as PH, FYVE, PX, PHD, C2 and SEC14 homology domains, mediate interactions between proteins and specific phospholipids. We recently cloned a 45‐kDa protein from rat olfactory epithelium, which is homologous to the yeast Sec14p phosphatidylinositol (PtdIns) transfer protein and we report here that this protein binds to PtdIns(3,4,5)P3 and far weaker to less phosphorylated derivatives of PtdIns. Expression of the p45 protein in COS‐1 cells resulted in accumulation of the protein in secretory vesicles and in the extracellular space. The secreted material contained PtdIns(3,4,5)P3. Our findings are the first report of a Sec14p‐like protein involved in transport out of a cell and, to the best of our knowledge, inositol‐containing phospholipids have not previously been detected in the extracellular space. Our findings suggest that p45 and phosphoinositides may participate in the formation of the protective mucus on nasal epithelium.
ISSN:1742-464X
1742-4658
DOI:10.1111/j.1742-4658.2005.04955.x