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Expression and disulfide-bond connectivity of the second ligand-binding repeat of the human LDL receptor

S Bieri1, J T Djordjevic, N Jamshidi

  • 1Department of Biochemistry, University of Queensland, Brisbane, Australia.

FEBS Letters
|September 11, 1995
PubMed

Insights

Researchers elucidated the disulfide bond connectivity in the second ligand-binding repeat of the human LDL receptor (LDLR). This finding reveals a structural paradigm for LDL receptor ligand-binding repeats.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Medicine

Background:

  • The human LDL receptor (LDLR) plays a crucial role in cholesterol metabolism.
  • Its ligand-binding (LB) domain comprises seven repeats, each with three disulfide bonds.
  • The second LB repeat is essential for efficient LDL binding.

Purpose of the Study:

  • To determine the precise disulfide bond connectivity within the second LB repeat of the human LDLR.
  • To investigate if this connectivity pattern is conserved within the LDLR LB domain.

Main Methods:

  • Expression and purification of the second LB repeat of the human LDLR.
  • Folding of the purified repeat to obtain a single, fully oxidized isomer.
  • Selective reduction and alkylation of cysteine residues to map disulfide bonds.

Main Results:

  • The second LB repeat was successfully expressed, purified, and folded.
  • Disulfide bond connectivity was determined to be I-III, II-V, and IV-VI.
  • This pattern matches the connectivity previously found in the amino-terminal repeat.

Conclusions:

  • The determined disulfide bond connectivity of the second LB repeat provides critical structural insights.
  • This unique disulfide-bonding pattern in the first two LB repeats may serve as a structural model for other LB repeats in the LDLR.
  • Understanding this structure can inform future research on LDLR function and related diseases.

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