抄録
We reported the seventh case of the internalization defective type of homozygous familial hypercholesterolemia (FH). LDL receptor activity was examined by cultured skin fibroblasts. LDL binding activity of the patient fibroblast was as much as normal fibroblasts at 37°C but at 4°C, the binding activity was about a half or one third of that of normal fibroblasts. Scatchard analysis of this binding activity revealed the dissociation constant of the patient fibroblasts was almost the same as that of normal fibroblast. But the numbers of receptor of the patient fibroblasts per cell was a half as much as normal fibroblasts. Bound LDL at 37°C was left from the cell surface into the medium rapidly when the temperature of the medium changed from 37°C to 4°C. The molecular weight of LDL receptor of patient's fibroblasts was about 130, 000 dalton determined by ligand blotting, which was the same as that of normal fibroblasts. It is suggested that some kinds of molecular defects exist in membrane spanning lesion or intracellular lesion of LDL receptor but this defect is not so big one as influencing molecular weight detected by SDS-PAGE.
