9316018 Subramani Peroxisomes are ubiquitous subcellular organelles present in most eukaryotic cells. They house a large array of enzymes intimately involved in lipid metabolism. The long-term goal of the work described here is to identify the protein components and to elucidate the mechanism by which matrix and membrane proteins are targeted to the peroxisome. Two peroxisomal targeting signals (PTS1 and PTS2) have already been implicated in the transport of matrix proteins to peroxisomes. Little is known regarding the signals that target membrane proteins to the organelle. The first goeal of this proposal is to elucidate the signal that targets proteins to the peroxisomal membrane. An understanding of the mechanism of peroxisomal protein import requires the ability to investigate the steps in an in vitro system. A cytosol-dependent permeabilized Chinese hamster ovary cell system has been developed for PTS1-containing proteins. The second goal of the proposal is the identification and purification of mammalian cytosolic components and peroxisomal membrane proteins required for import of PTS1 containing proteins. %%% The name "peroxisome" derives from the fact that the enzymes that produce and degrade hydrogen peroxide are localized in this organelle. However, perooxisomes also contain all or part of several other biochemical pathways. Part of the problem in assigning a single predominant function to this organelle is that the content of peroxisomal proteins varies between organisms, cell types and the environment of the cell or organism. Therefore, the studies proposed here will result in a greater understanding of the mechanisms involved in the biogenesis of this important organelle. ***
