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 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.
Related Citations:
Structural Analysis of Apolipoprotein A-I: Limited Proteolysis of Methionine-Reduced and-Oxidized Lipid-Free and Lipid-Bound Human Apo A-I Roberts, L.M., Ray, M.J., Shih, T.W., Hayden, E., Reader, M.M., Brouillette, C.G. (1997) Biochemistry 36: 7615
Truncation of the Amino Terminus of Human Apolipoprotein A-I Substantially Alters Only the Lipid-Free Conformation Rogers, D.P., Brouillette, C.G., Engler, J.A., Tendian, S.W., Roberts, L., Mishra, V.K., Anantharamaiah, G.M., Lund-Katz, S., Phillips, M.C., Ray, M.J. (1997) Biochemistry 36: 288
Structural Models of Human Apolipoprotein A-I Brouillette, C.G., Anantharamaiah, G.M. (1995) Biochim Biophys Acta 1256: 103
Organizational Affiliation:
Department of Organic Chemistry, Southern Research Institute, Birmingham, AL 35205, USA. borhani@sri.org
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