Ammonium chloride causes reversible inhibition of low density lipoprotein receptor recycling and accelerates receptor degradation.

Grant, Kevin I.; Casciola, Livia Angela Flavia; Coetzee, Gerhard A.; Sanan, David A.; Gevers, Wieland; Westhuyzen, Deneys R. van der

doi:10.1016/s0021-9258(19)39699-1

Cited by 32 publications

(6 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…degraded in 3 h) compared to the insignificant degradation observed with ammonium chloride alone (Figure 4) or LDL alone (Grant et al, 1990). However, in FH 1 cells, degradation of only 40% of the mutant receptors occurred during the incubation with LDL and ammonium chloride.…”

Section: Resultsmentioning

confidence: 82%

“…Ligand-Induced Loss of Surface Receptors. Incubation of normal fibroblasts with LDL or /SVLDL in the presence of ammonium chloride leads to a rapid decrease in the level of surface LDL receptors (Grant et al, 1990). This is believed to be due to intracellular trapping of receptors through inhibition of acid-dependent ligand dissociation.…”

Section: Resultsmentioning

confidence: 99%

“…This is believed to be due to intracellular trapping of receptors through inhibition of acid-dependent ligand dissociation. Trapped receptors are degraded with a half-life of approximately 2 h (Grant et al, 1990). Since these effects depend on ligand binding, it was of interest to determine what fraction of the 0 20 40 60 80 12Sl-LDL(ug/ml) Figure 2: Cell association and degradation of 125I-LDL at 37 °C in normal and FHla fibroblasts.…”

Section: Resultsmentioning

confidence: 99%

“…Evidence was suggested that LDL receptors function as oligomers, possibly tetramers (Mahley & Innerarity, 1983;Grant et al, 1990; Innerarity, 1990). It has been proposed that in the binding of LDL, the four receptor molecules of a tetramer each bind one molecule of ligand, whereas in the binding of /3VLDL, the multiple apoE molecules on a single particle simultaneously saturate all the receptors of the oligomeric structure (Mahley & Innerarity, 1983 least partially aggregated on the cell surface (Van Driel et al, 1987).…”

Section: Discussionmentioning

confidence: 99%

“…The fibroblast cell line FHla was the same as that used by Leitersdorf et al (1989) to determine the FH1 mutation. Cells were cultured and LDL receptors up-regulated for 48 h in LPDS-containing medium all as described before (Grant et al, 1990). In some cases, cells were down-regulated by a 48-h treatment with DMEM/LPDS containing 1 pg/mL 25-hydroxycholesterol and 12 pg/mL cholesterol.…”

Section: Methodsmentioning

confidence: 99%

See 4 more Smart Citations

Low-density lipoprotein receptor point mutation results in expression of both active and inactive surface forms of the same mutant receptor

Coetzee²,

Gevers³

et al. 1992

Biochemistry

View full text Add to dashboard Cite

LDL receptors, expressed in cultured fibroblasts from patients homozygous for the FH Afrikaner-1 (FH1) mutation (Asp206 to Glu), are transported from the endoplasmic reticulum (ER) to the Golgi apparatus more slowly than in normal cells. In the present study, binding characteristics of FH1 cells for lipoprotein ligands (LDL and beta VLDL) and for receptor-specific monoclonal antibodies pointed to the existence of two surface forms of the same mutant receptor. One of these forms bound lipoproteins with normal high affinity whereas another did not. Binding studies of transfected hamster cells expressing only the mutant human gene confirmed the single-gene origin of the different forms. The existence of functionally distinct forms of the receptor protein was supported by the observation that only lipoprotein-binding receptor molecules were trapped intracellularly and degraded following ammonium chloride treatment of cells in the presence of ligand. The lipoprotein-binding receptor population was indistinguishable from normal receptors with respect to its affinity for LDL and beta VLDL, uptake and degradation of lipoprotein, and receptor recycling. Ligand blotting versus immunoblotting of receptors revealed normal-sized mutant receptors that were not recognized by lipoprotein ligand. Despite these differences, both mutant forms of the receptor were degraded at rates similar to those of normal receptors. We propose that the single amino acid substitution in this receptor interferes with the folding and/or posttranslational processing of precursor molecules in such a way that receptors adopt alternative stable structures.

show abstract

Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%