Poster: Protein targeting & vesicular trafficking

Abs # 644: Identification and characterization of Arabidopsis tail-anchored integral membrane proteins

Presenter:	Dhanoa, Preetinder K, pdhanoa@uoguelph.ca
Authors	Dhanoa, Preetinder K (A)   Henderson, Matthew  (B)   Andrews, David W (B)   Mullen, Robert T (A)
Affiliations:	(A): University of Guelph, Department of Botany (B): McMaster University, Department of Biochemistry

Tail anchored (TA) membrane proteins possess a single hydrophobic segment at their C terminus and are inserted post-translationally into a target membrane such that the majority of the protein faces the cytosol. Although the biogenesis of several TA proteins have been well studied in mammals and yeast, only a relative few TA proteins have been examined in plants. In order to identify other plant TA proteins, we searched the Arabidopsis thaliana proteome using the computer algorithm TAMP (for Tail Anchored Membrane Proteins). Specifically, we challenged TAMP to identify (based on a Kyte-Doolittle hydropathy index) open reading frames lacking a putative signal sequence but possessing a single putative membrane-spanning domain within the last 50 residues of the protein. In total, 385 candidate TA proteins were identified in the Arabidopsis proteome, including several novel isoforms of ascorbate peroxidase and cytochrome b₅, a putative mitochondrial membrane fission protein, three isoforms of the 20 kDa subunit of the translocase of the outer mitochondrial membrane, and 40 different soluble NSF attachment receptor (SNARE) proteins that are proposed to be involved in various aspects of membrane trafficking. Notably, 270 of the candidate TA proteins were of unknown function. A comparative analysis of all Arabidopsis TA proteins in terms of their subcellular localization, membrane integration/assembly events and molecular targeting signals is currently being performed. The results of our preliminary experiments will be discussed. Supported by NSERC grant 217291 to RTM.