Uptake and degradation of filamentous actin and vitamin D-binding protein in the rat.
Tissue uptake and degradation of 125I-tyramine-cellobiose-labelled filamentous actin, vitamin D-binding protein (DBP) and actin-DBP complex were studied in the rat. Actin and actin-DBP complex were cleared from plasma at a faster rate than was DBP. About 40% of injected actin was recovered in the liver between 10 and 30 min after administration. Of the total radioactivity recovered in the liver, about 35% and 40% was detected in parenchymal and endothelial cells respectively when labelled actin or DBP-actin complex was injected intravenously. When labelled DBP alone was injected, approx. 55% of the radioactivity recovered in liver was in the Kupffer cells. These results suggest that actin is targeting the DBP-actin complex to the endothelial and parenchymal liver cells. Filamentous actin was also taken up in large amounts and at a rapid rate in parenchymal as well as non-parenchymal liver cells in vitro. Our data indicate that the rat has a mechanism to clear actin and the DBP-actin complex from plasma and that both parenchymal and non-parenchymal liver cells are involved in this process.
Dueland
S
S
Institute for Nutrition Research, University of Oslo, Norway.
Nenseter
M S
MS
Drevon
C A
CA
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D007457:Iodine Radioisotopes; D007700:Kinetics; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D011485:Protein Binding; D011865:Radioisotope Dilution Technique; D051381:Rats; D011919:Rats, Inbred Strains; D014809:Vitamin D-Binding Protein / Q000302:isolation & purification / Q000378:metabolism*
D000199:Actins; D007457:Iodine Radioisotopes; D014809:Vitamin D-Binding Protein