Endocytosis of formaldehyde-denatured serum albumin by nonparenchymal liver cells in vitro.
The uptake and degradation of 125I-labeled formaldehyde-denatured serum albumin in nonparenchymal rat liver cells were studied in vitro. Nonparenchymal cells bound formaldehyde-denatured serum albumin at two types of binding site, one with a high affinity and one a low affinity. The number of high affinity binding sites was approx. 10(5) per cell and the association constant, Ka 10(8) M-1. Inhibition of protein synthesis with cycloheximide did not affect the uptake and degradation of formaldehyde-denatured serum albumin suggesting reutilization of the binding sites. The presence of monensin-reduced uptake and degradation to less than 10% of control values. Pronase treatment of nonparenchymal liver cells completely abolished the uptake and degradation of the ligand. The uptake mechanism was not specific for formaldehyde-denatured serum albumin. Unlabeled acetylated, as well as malondialdehyde treated, serum albumin reduced the uptake of 125I-labeled formaldehyde-denatured serum albumin as effectively as unlabeled formaldehyde-denatured serum albumin itself.
D000818:Animals; D004705:Endocytosis; D005557:Formaldehyde; D007976:Leupeptins / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008247:Lysosomes / Q000502:physiology; D008985:Monensin / Q000494:pharmacology; D011487:Protein Conformation; D011489:Protein Denaturation; D051381:Rats; D012709:Serum Albumin / Q000378:metabolism*; D013329:Structure-Activity Relationship
D007976:Leupeptins; D012709:Serum Albumin; D005557:Formaldehyde; D008985:Monensin; C032854:leupeptin