Deletion in the first cysteine-rich repeat of low density lipoprotein receptor impairs its transport but not lipoprotein binding in fibroblasts from a subject with familial hypercholesterolemia

Journal Article · Mon Oct 31 23:00:00 EST 1988 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.85.21.7912· OSTI ID:5606530

Leitersdorf, E; Hobbs, H H; Fourie, A M; Jacobs, M; Van Der Westhuyzen, D R; Coetzee, G A ^[1]

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1. Univ. of Texas Southwestern Medical Center, Dallas (USA)

The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each {approx} 40 amino acids long. Previous studies showed that if the first repeat of the ligand-binding domain (encoded by exon 2) is deleted, the receptor fails to bind an anti-LDL receptor monoclonal antibody (IgG-C7) but continues to bind LDL with high affinity. Cultured fibroblasts from a Black South African Xhosa patient (TT) with the clinical syndrome of homozygous familial hypercholesterolemia demonstrated high-affinity cell-surface binding of {sup 125}I-labeled LDL but not {sup 125}I-labeled IgG-C7. previous haplotype analysis, using 10 restriction fragment length polymorphic sites, suggested that the patient inherited two identical LDL receptor alleles. The polymerase chain reaction technique was used to selectively amplify exon 2 of the LDL receptor gene from this patient. Sequence analysis of the amplified fragment disclosed a deletion of six base pairs that removes two amino acids, aspartic acid and glycine, from the first cysteine-rich ligand binding repeat. The mutation creates a new Pst I restriction site that can be used to detect the deletion. The existence of this mutant allele confirms that the epitope of IgG-C7 is located in the first cysteine-rich repeat and that this repeat is not necessary for LDL binding. The mutant gene produced a normally sized 120-kilodalton LDL receptor precursor protein that matured to the 160-kilodalton form at less than one-fourth the normal rate.

• OSTI ID: 5606530
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 85:21; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550401* -- Genetics-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFRICA
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BIOCHEMISTRY
CHEMISTRY
CHOLESTEROL
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DISEASES
DNA SEQUENCING
ELECTRON CAPTURE RADIOISOTOPES
FIBROBLASTS
GENE AMPLIFICATION
HEREDITARY DISEASES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
LIGANDS
LIPIDS
LIPOPROTEINS
MEMBRANE PROTEINS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PATIENTS
PROTEINS
RADIOISOTOPES
RECEPTORS
RFLPS
SOMATIC CELLS
SOUTH AFRICA
STEROIDS
STEROLS
STRUCTURAL CHEMICAL ANALYSIS