title: Activity-associated effect of LDL receptor missense variants located in the cysteine-rich repeats.
abstract: BACKGROUND
  The LDL receptor (LDLR) is a Class I transmembrane protein critical for the clearance of cholesterol-containing lipoprotein particles. The N-terminal domain of the LDLR harbours the ligand-binding domain consisting of seven cysteine-rich repeats of approximately 40 amino acids each. Mutations in the LDLR binding domain may result in loss of receptor activity leading to familial hypercholesterolemia (FH). In this study the activity of six mutations located in the cysteine-rich repeats of the LDLR has been investigated.
  
  
  METHODS
  CHO-ldlA7 transfected cells with six different LDLR mutations have been used to analyse in vitro LDLR expression, lipoprotein binding and uptake. Immunoblotting of cell extracts, flow cytometry and confocal microscopy have been performed to determine the effects of these mutations. In silico analysis was also performed to predict the mutation effect.
  
  
  CONCLUSIONS
  From the six mutations, p.Arg257Trp turned out to be a non-pathogenic LDLR variant whereas p.Cys116Arg, p.Asp168Asn, p.Asp172Asn, p.Arg300Gly and p.Asp301Gly were classified as binding-defective LDLR variants whose effect is not as severe as null allele mutations.
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Etxebarria
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Benito-Vicente
authors.affiliation: Progenika Biopharma, a Grifols Company, Derio, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Stef
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain.
authors.forename: H
authors.initials: H
authors.lastname: Ostolaza
authors.affiliation: Progenika Biopharma, a Grifols Company, Derio, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Palacios
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain. Electronic address: cesar.martin@ehu.es.
authors.forename: C
authors.initials: C
authors.lastname: Martin
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D016466:CHO Cells; D003198:Computer Simulation; D003412:Cricetulus; D003545:Cysteine; D005434:Flow Cytometry; D020022:Genetic Predisposition to Disease; D006938:Hyperlipoproteinemia Type II / Q000235:genetics* / Q000378:metabolism; D008074:Lipoproteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D010641:Phenotype; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: C573412:LDLR protein, human; D008074:Lipoproteins; D011973:Receptors, LDL; D003545:Cysteine
keywords: Familial hypercholesterolemia; LDLR; Ligand binding domain; Mutation class defect; Mutations