Figure 6. Binding, uptake, and degradation of VLDL at 37°C.

(A) Uptake and degradation of VLDL was measured in wild-type and mutant hepato­cytes after 1 hour of incubation with 20 μg/ml of ¹²⁵I-VLDL. The bars represent the sum of binding and internalization under these conditions, or the amount of degradation as determined by acid-soluble, non-chloroform–extractable counts in the medium. Binding plus uptake was reduced 2.7-fold in Sdc1^–/– cells. Degradation was reduced by nearly 6-fold. (B) Hepatocytes isolated from Sdc1^–/– mice treated with AdSdc1 showed enhanced binding and uptake and increased degradation of ¹²⁵I-VLDL compared with hepatocytes isolated from Sdc1^–/– mice treated with AdGFP (P < 0.02). (C) Binding and uptake were also measured in hepatocytes isolated from wild-type, Sdc1^–/–, Ldlr^–/–, and Ldlr^–/–Ndst1^f/fAlbCre⁺ mice. Uptake and binding were reduced 2-fold in the Sdc1^–/– and Ldlr^–/–Ndst1^f/fAlbCre⁺ hepatocytes compared with wild-type (P < 0.001), while a slight change was observed in Ldlr^–/– compared with wild-type (P < 0.05).