Import of proteins into peroxisomes

Peroxisomes are organelles that confine an important set of enzymes within their single membrane boundaries. In man, a wide variety of genetic disorde rs is caused by loss of peroxisome function. In the most severe cases, the clinical phenotype indicates that abnormalities begin to appear during embr yological development. In less severe cases, the quality of life of adults is affected. Research on yeast model systems has contributed to a better un derstanding of peroxisome formation and maintenance. This framework of know ledge has made it possible to understand the molecular basis of most of the peroxisome biogenesis disorders. Interestingly, most peroxisome biogenesis disorders are caused by a failure to target peroxisomal proteins to the or ganellar matrix or membrane, which classifies them as protein targeting dis eases. Here we review recent fundamental research on peroxisomal protein ta rgeting and discuss a few burning questions in the field concerning the ori gin of peroxisomes. (C) 1999 Elsevier Science B.V. All rights reserved.