Crystal structure of truncated human apolipoprotein A-I suggests a lipid-bound conformation

Proc Natl Acad Sci U S A. 1997 Nov 11;94(23):12291-6. doi: 10.1073/pnas.94.23.12291.


The structure of truncated human apolipoprotein A-I (apo A-I), the major protein component of high density lipoprotein, has been determined at 4-A resolution. The crystals comprise residues 44-243 (exon 4) of apo A-I, a fragment that binds to lipid similarly to intact apo A-I and that retains the lipid-bound conformation even in the absence of lipid. The molecule consists almost entirely of a pseudo-continuous, amphipathic alpha-helix that is punctuated by kinks at regularly spaced proline residues; it adopts a shape similar to a horseshoe of dimensions 125 x 80 x 40 A. Four molecules in the asymmetric unit associate via their hydrophobic faces to form an antiparallel four-helix bundle with an elliptical ring shape. Based on this structure, we propose a model for the structure of apo A-I bound to high density lipoprotein.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Apolipoprotein A-I / chemistry*
  • Apolipoprotein A-I / metabolism
  • Binding Sites
  • Crystallography, X-Ray
  • Humans
  • Lipid Metabolism*
  • Lipids / chemistry
  • Molecular Sequence Data
  • Protein Binding
  • Protein Conformation*


  • Apolipoprotein A-I
  • Lipids