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

E. Leitersdorf, H. H. Hobbs, A. M. Fourie, M. Jacobs, D. R. Van der Westhuyzen, G. A. Coetzee

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each ~40 amino acids long. Previous studies by van Driel et al. [van Driel, I.R., Goldstein, J.L., Sudhof, T.C. & Brown, M.S. (1987) J. Biol. Chem. 262, 17443-17449] 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 125I-labeled LDL but not 125I-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. Thus, deletion of two amino acids within the first cysteine-rich repeat retards receptor transport from the endoplasmic reticulum to the cell surface, in contrast to deletion of the entire first repeat, which has no effect on receptor maturation.

Original languageEnglish (US)
Pages (from-to)7912-7916
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume85
Issue number21
StatePublished - 1988

Fingerprint

Hyperlipoproteinemia Type II
LDL Receptors
Lipoproteins
Cysteine
Fibroblasts
LDL Lipoproteins
Immunoglobulin G
Ligands
Amino Acids
Exons
Alleles
Protein Precursors
Aspartic Acid
Base Pairing
Endoplasmic Reticulum
Glycine
Haplotypes
Genes
Sequence Analysis
Epitopes

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

@article{df1a64e8c5264048916aefc31197052b,
title = "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",
abstract = "The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each ~40 amino acids long. Previous studies by van Driel et al. [van Driel, I.R., Goldstein, J.L., Sudhof, T.C. & Brown, M.S. (1987) J. Biol. Chem. 262, 17443-17449] 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 125I-labeled LDL but not 125I-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. Thus, deletion of two amino acids within the first cysteine-rich repeat retards receptor transport from the endoplasmic reticulum to the cell surface, in contrast to deletion of the entire first repeat, which has no effect on receptor maturation.",
author = "E. Leitersdorf and Hobbs, {H. H.} and Fourie, {A. M.} and M. Jacobs and {Van der Westhuyzen}, {D. R.} and Coetzee, {G. A.}",
year = "1988",
language = "English (US)",
volume = "85",
pages = "7912--7916",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "21",

}

TY - JOUR

T1 - 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

AU - Leitersdorf, E.

AU - Hobbs, H. H.

AU - Fourie, A. M.

AU - Jacobs, M.

AU - Van der Westhuyzen, D. R.

AU - Coetzee, G. A.

PY - 1988

Y1 - 1988

N2 - The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each ~40 amino acids long. Previous studies by van Driel et al. [van Driel, I.R., Goldstein, J.L., Sudhof, T.C. & Brown, M.S. (1987) J. Biol. Chem. 262, 17443-17449] 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 125I-labeled LDL but not 125I-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. Thus, deletion of two amino acids within the first cysteine-rich repeat retards receptor transport from the endoplasmic reticulum to the cell surface, in contrast to deletion of the entire first repeat, which has no effect on receptor maturation.

AB - The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each ~40 amino acids long. Previous studies by van Driel et al. [van Driel, I.R., Goldstein, J.L., Sudhof, T.C. & Brown, M.S. (1987) J. Biol. Chem. 262, 17443-17449] 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 125I-labeled LDL but not 125I-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. Thus, deletion of two amino acids within the first cysteine-rich repeat retards receptor transport from the endoplasmic reticulum to the cell surface, in contrast to deletion of the entire first repeat, which has no effect on receptor maturation.

UR - http://www.scopus.com/inward/record.url?scp=0023779566&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023779566&partnerID=8YFLogxK

M3 - Article

C2 - 3263645

AN - SCOPUS:0023779566

VL - 85

SP - 7912

EP - 7916

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 21

ER -