title: Beta-sheet secondary structure of an LDL receptor domain from complement factor I by consensus structure predictions and spectroscopy.
abstract: Low density lipoprotein receptor domains (LDLrs) represent a large cell surface receptor superfamily of consensus length 39 residues. Alignment of 194 sequences indicated highly conserved Cys and Asp/Glu residues, and a consensus secondary structure with three beta-strands was predicted. Sequence threading against known protein folds indicated consistency with small beta-sheet proteins. Complement factor I contains two LDLrs, and the second of these was successfully expressed using a bacterial pGEX system. FT-IR spectroscopy on this indicated a small amount of beta-sheet together with turns and loops. LDLr is proposed to have a beta-sheet structure in which the five biologically important Asp/Glu residues are located on an exposed loop.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Oxford, UK.
authors.forename: C G
authors.initials: CG
authors.lastname: Ullman
authors.forename: P I
authors.initials: PI
authors.lastname: Haris
authors.forename: K F
authors.initials: KF
authors.lastname: Smith
authors.forename: R B
authors.initials: RB
authors.lastname: Sim
authors.forename: V C
authors.initials: VC
authors.lastname: Emery
authors.forename: S J
authors.initials: SJ
authors.lastname: Perkins
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D017244:Complement Factor I / Q000737:chemistry*; D016384:Consensus Sequence; D006801:Humans; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011973:Receptors, LDL / Q000737:chemistry*; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D011973:Receptors, LDL; D017244:Complement Factor I