Protein Targeting and Vesicular Trafficking
Peterman, Kaye , Oddone, Alessandra , Dankwa, Selasi .
Functional characterization of the Sec14 domain of patellin1.
Patellin1 (PATL1) is a phosphoinositide-binding protein which localizes to the expanding cell plate where it is hypothesized to function in membrane recycling events. PATL1 is one of a family of Arabidopsis proteins which are characterized by a variable N-terminal domain and two domains found in membrane trafficking proteins (Sec14 and GOLD). The focus of this study is on the function of the Sec14 domain of PATL1. Sec14p, which is essential for vesicle traffic from the TGN in yeast, is the defining member of one family of phosphatidyl inositol lipid transfer proteins (PITPs). PITPs play diverse roles in membrane trafficking and PI signaling, therefore functional characterization of the Sec14 domains of the PATLs is likely to provide insight into how they interface with PI metabolism in plants. Phylogenetic analyses indicate that the PATLs are more closely related to the human sec14-like proteins than to yeast Sec14p. Interestingly the PATLs, like the human sec14-like proteins, fail to rescue the yeast sec14-1ts mutant. These results indicate that the Sec14 domain of the PATLs is functionally distinct from yeast sec14p. Homology-based modeling studies are in progress to determine the structural basis for this functional difference. Phosphoinositide binding studies are being used to determine the lipid-binding specificity of the PATL1 Sec14 domain. PATL1 binds the phosphoinositides, PtdIns5P, PtdIns(4,5)P2 and PtdIns(3)P with a strong preference for PtdIns5P. However the PATL1 protein sequence has two potential PI-binding sites, the Sec14 domain and a lysine-rich motif found at the C-terminus. The phosphoinositide-binding activity of PATL1 and a PATL1 truncation which lacks the lysine-rich motif will be presented.
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1 - Wellesley College, Biological Sciences, 106 Central St., Wellesley, MA, 02481, USA
2 - Wellesley College, Biological Sciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM