In the past decade several reports have appeared which suggest that peroxisomes play a central role in isoprenoid/cholesterol biosynthesis. These suggestions were based primarily on the reported finding of several of the enzymes of the presqualene segment of the biosynthetic pathway in peroxisomes. More recently, however, conflicting results have been reported raising doubt about the postulated...

Translocation of proteins across membranes of the endoplasmic reticulum, mitochondrion, and chloroplast has been shown to be mediated by targeting signals present in the transported proteins. To test whether the transport of proteins into peroxisomes is also mediated by a peptide targeting signal, we have studied the firefly luciferase gene that encodes a protein transported to peroxisomes in b...

During the past few years, we have witnessed a paradigm shift in our long-standing concept of peroxisome biogenesis. Recent biochemical and morphological studies have revealed a primary role of the endoplasmic reticulum (ER) in the de novo formation of peroxisomes, thus challenging the prevalent model invoking growth and division of pre-existing peroxisomes. Importantly, a novel sorting process...

Peroxisomes are morphologically characterized by a single limiting membrane and a finely granular matrix, and some of them contain crystalline nucleoids (1, 2). Application of the alkaline 3,3'-diaminobenzidine (DAB) method, which visualizes the peroxidatic activity of catalase (3, 4) in normal liver, has revealed electron-dense reaction product in the matrix of peroxisomes, but none in the cyt...

Background: Pex5p translocates the cargo proteins into peroxisomes. Results:Mammalian RING peroxins, the Pex10p Pex12p complex, catalyze Lys-linked, multiple monoubiquitination of Pex5p, assuring efficient export of Pex5p from peroxisomes. Conclusion: Distinct Lysand Cys-linked modes of Pex5p ubiquitination control Pex5p-mediated matrix protein import. Significance: This work provides the first...

The distribution of enzymes involved in purine degradation in fish and crustaceous liver was examined by centrifugation in a sucrose density gradient. In mackerel, yellow mackerel, and prawn liver and mantis club hepatopancreas, uricase and allantoinase were located only in the peroxisomes and in the soluble fraction from broken peroxisomes, and allantoicase was located only in the peroxisomes....

Upon differential centrifugation of rat liver homogenate, the enzyme acyl-CoA:dihydroxyacetone-phosphate acyltransferase (EC 2.3.1.42) was found to be localized in the light mitochondrial (L) fraction which is enriched with lysosomes and peroxisomes. Peroxisomes were separated from lysosomes in a density gradient centrifugation using rats which were injected with Triton WR 1339. By comparing th...

Peroxisomes play diverse and important roles in plants. The functions of peroxisomes are dependent upon their steady state protein composition which in turn reflects the balance of formation and turnover of the organelle. Protein import and turnover of constituent peroxisomal proteins are controlled by the state of cell growth and environment. The evolutionary origin of the peroxisome and the r...

The H2O2 byproduct of fatty acid catabolism in plant peroxisomes is removed in part by a membrane-associated antioxidant system that involves both an ascorbate peroxidase and a monodehydroascorbate reductase (MDAR). Despite descriptions of 32-kDa MDAR polypeptides in pea and castor peroxisomal membranes and cDNA sequences for several 'cytosolic' MDARs, the genetic and protein factors responsibl...