Physiology and pathophysiology of cell organelles

Abstract

Peroxisomes are round or oval organelles with a finely granular matrix surrounded by a single membrane and are especially found in liver and kidney cells. Catalase-positive structures or microperoxisomes are, however, found in all eucaryotic cells except mature red blood cells. Enzyme proteins (approximately fifty) destined for peroxisomes are synthesized in free cytosolic ribosomes and are incorporated in the matrix of forming organelles with the aid of two signal peptides: a carboxy terminal SKL-tripeptide and possibly an aminoterminal undecapeptide. The functions of peroxisomes include, inter alia, extramitochondrial fi-oxidation (espe­cially very long chain fatty acids), synthesis of plasmalogens and other ether lipids and metabolism of hydrogen peroxide.