Sequence and structure of the membrane-associated peptide of glycophorin A.
Glycophorin A (GPA) has been reconstituted into dimyristoylphosphatidylcholine vesicles and digested with proteinase K to identify the membrane domain and to characterize its structure and orientation. After digestion of the inner and outer domain of GPA by protease action restricted to the aqueous phase, a protected peptide migrates on an electrophoresis gel as a 7.5-kDa dimer (His66-Ile95). The secondary structure and orientation in a lipid bilayer of the 7.5-kDa dimer have been studied by Fourier transform infrared spectroscopy. Our proteolytic and spectroscopic data are in agreement with a topological model in which the His66-Glu72 peptide adopts a beta-sheet conformation and is oriented parallel to the lipid-water interface and the Ile73-Ile95 domain is helical and oriented parallel to the lipid acyl chains, in a transmembrane configuration. Digestion of the domain protruding to the outside of the liposome generates "head-head" and "head-tail" dimers of 16 and 38 kDa, respectively. This observation is discussed in terms of the specificity of the dimer formation process.
Challou
N
N
Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Free University Brussels, Belgium.
Goormaghtigh
E
E
Cabiaux
V
V
Conrath
K
K
Ruysschaert
J M
JM
D000595:Amino Acid Sequence; D004134:Dimyristoylphosphatidylcholine; D019286:Endopeptidase K; D006021:Glycophorins / Q000737:chemistry*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D017433:Protein Structure, Secondary; D012697:Serine Endopeptidases; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
D006021:Glycophorins; D008565:Membrane Proteins; D010446:Peptide Fragments; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D019286:Endopeptidase K; D004134:Dimyristoylphosphatidylcholine