A proteomic analysis of lipid raft and GPI anchored proteins in Caenorhabditis elegans

Glycosylphosphatidylinositol (GPI) anchored proteins are a unique group of membrane proteins found on the surface and certain intracellular compartments of eukaryotic cells. They are bound to the membrane by a GPI moiety and have a
number of important functions, including digestion, endocytosis and signal transduction. GPI anchored proteins also reside within lipid rafts, which are microdomains on the phospholipid bilayer composed of sphingolipids and cholesterol. Rafts are thought to be capable of forming semi-stable “islands”of lipids and proteins that act as a platform for a number of important cellular processes, such as T-cell activation, caveolin mediated endocytosis and protein compartmentalisation. The majority of research into rafts has been carried out in single cellular organisms or cell cultures, and their importance within development has been poorly understood.

In this project a proteomic analysis of lipid raft and GPI anchored proteins was made for the proteome of the model organism Caenorhabditis elegans. We found a total of
327 predicted GPI anchored proteins from the C. elegans genome via a novel four-program prediction method and validated three of those proteins with mass spectrometric (MS) identification. The GPI biosynthesis pathway genes of C. elegans were also elucidated via a bioinformatics search. 41 lipid raft proteins were identified
using MS, which accounts for the largest number of such proteins found in the worm. This project will hopefully become a starting point for the research of GPI anchored
proteins and lipid rafts within the nematode, and shine a light on the properties of these important classes of proteins within the context of a developmentally complex
organism.