Crystal structure of truncated human apolipoprotein A-I suggests a lipid-bound conformation.
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Borhani DW, Rogers DP, Engler JA, Brouillette CG
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.
- PubMed ID
- 9356442 [ View in PubMed]
- Abstract
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.