Re-uptake of nascent low-density lipoproteins by HepG2 cells.
The kinetics and specificity of the interaction of nascent HepG2 LDL with the HepG2 LDL receptor were examined. 125I-Labeled HepG2 LDL and plasma LDL were bound by HepG2 cells in a specific and saturable manner at 4 degrees C. Competition studies with HepG2 LDL and plasma LDL indicated that both ligands bound to the same receptor. Scatchard analyses of the specific 4 degrees C-binding data revealed a Kd of 75 nM for HepG2 LDL and a Kd of 30 nM for plasma LDL suggesting that HepG2 LDL bind less efficiently to the HepG2 LDL receptor than plasma LDL. Binding, internalization and degradation studies carried out at 37 degrees C indicated that HepG2 cells are capable of catabolizing their own nascent LDL; however, under normal experimental conditions re-uptake of nascent LDL is quantitatively insignificant.
Hara
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Department of Molecular and Nuclear Medicine, University of California, Donner Laboratory, Berkeley 94720.
McCall
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MR
Forte
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TM
D001667:Binding, Competitive; D002460:Cell Line / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D008077:Lipoproteins, LDL / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D010316:Particle Size; D011973:Receptors, LDL / Q000378:metabolism*
D007457:Iodine Radioisotopes; D008077:Lipoproteins, LDL; D011973:Receptors, LDL