DISTRIBUTION OF LECTIN ACTIVITY IN MITOCHONDRIA OF SUGAR-BEET ROOTS -LECTIN ACTIVITY IN THE MITOCHONDRIAL-MEMBRANES AND MATRIX

The age-dependent distribution of lectin activity in submitochondrial fractions of sugar beet (Beta vulgaris L.) roots was studied by the me thod of the agglutination of trypsinized rabbit erythrocytes. Lectins were found in the mitochondrial membranes and matrix. In the outer mem brane, carbohydrate-binding sites of lectins were only found on the si de facing the cytoplasm. In the inner membrane, carbohydrate-binding s ites of lectins were exposed to both the intermembranal space and matr ix. The outer mitochondrial membrane had the greatest lectin activity, whereas, in the inner-membrane/matrix interface, lectin activity was the lowest. The lectin activities of the outer membrane and the extern al side of the inner membrane decreased with root age. Conversely, the lectin activities of the matrix-exposed side of the inner membrane an d the matrix itself increased with root maturation. The possible parti cipation of membrane and matrix lectins in the regulation of the funct ional activity of mitochondria is discussed.