Heterogeneity of lysosomes originating from rat liver parenchymal cells. Metabolic relationship of subpopulations separated by density-gradient centrifugation.
1. A crude lysosomal fraction obtained by differential centrifugation of a rat liver homogenate was subjected to zonal centrifugation in iso-osmotic self-generating gradients composed of modified colloidal silica (Percoll). Analysis of relevant marker-enzyme activities shows a continuous band of considerably purified lysosomal particles in the density range 1.04--1.11 g/ml. 2. A relationship between age and buoyant density of the parenchymal lysosomal subpopulations is indicated by the distribution of 125I-labelled asialoglycoproteins in the heterogeneous lysosomes during the catabolism of the glycoprotein. The labelled asialoglycoprotein first appeared in lysosomal particles of low density, which with time progressively acquired a higher density. Furthermore, 30 min after administration the 125I-labelled asialocaeruloplasmin recovered in the light lysosomes was less degraded than the material recovered in the heavy lysosomes. 3. A lysosomal enzyme (arylsulphatase) was found to possess considerably higher isoelectric points in the heavy lysosomes than in the light lysosomes, which is consistent with a relationship between age and density of the lysosomes.
D000818:Animals; D001212:Asialoglycoproteins; D002499:Centrifugation, Density Gradient; D002570:Ceruloplasmin / Q000031:analogs & derivatives / Q000378:metabolism; D002850:Chromatography, Gel; D066298:In Vitro Techniques; D007525:Isoelectric Focusing; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008247:Lysosomes / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats
D001212:Asialoglycoproteins; D011506:Proteins; C003950:asialoceruloplasmin; D002570:Ceruloplasmin