Glycophorin A

Rice University

Department of Biochemistry and Cell Biology

Glycophorin A

Background information

Glycophorin A (GpA) is a 131 amino acid protein that spans the membrane once and presents its amino-terminal end at the extra-cellular surface of the human red blood cell. Its 23 residue hydrophobic transmembrane domain has been shown to mediate non-covalent dimerization of the protein under conditions of SDS-PAGE (and in a number of other detergents), in artificial bilayers, and in biological membranes. The GpA system has been studied by a variety of biochemical and biophysical techniques aimed at understanding the basis of this self-association; accordingly, GpA serves as a model for how analogous systems might be studied.

Selected primary literature

The ensuing list of papers includes many of the important developments in the field of GpA transmembrane domain folding, dimerization and stability. No attempt at completeness is made.

Mutagenesis and interpretations
"Structure-based prediction of the stability of transmembrane helix-helix interactions: The sequence dependence of glycophorin A dimerization"
KR MacKenzie and DM Engelman PNAS (1998) 95, 3583-3590.

"Helix-helix packing in a membrane-like environment"
I Mingarro, A Elofsson and G von Heijne J Mol Biol (1997) 272(4), 633-41

"Ala-insertion scanning mutagenesis of the glycophorin A transmembrane helix: a rapid way to map helix-helix interactions in integral membrane proteins"
I Mingarro, P Whitley, MA Lemmon and G von Heijne Protein Sci (1996) 5(7), 1339-41

"A dimerization motif for transmembrane a-helices"
MA Lemmon, HR Treutlein, PD Adams, AT Brünger and DM Engelman Nat Struct Biol (1994) 1(3), 157-63

"Sequence specificity in the dimerization of transmembrane a-helices"
MA Lemmon, JM Flanagan, HR Treutlein, J Zhang and DM Engelman Biochemistry (1992) 31(51), 12719-25

"Glycophorin A dimerization is driven by specific interactions between transmembrane a-helices"
MA Lemmon, JM Flanagan, JF Hunt, BD Adair, BJ Bormann, CE Dempsey and DM Engelman J Biol Chem (1992) 267(11), 7683-9

"Synthetic peptides mimic the assembly of transmembrane glycoproteins"
BJ Bormann, WJ Knowles and VT Marchesi J Biol Chem (1989) 264(7), 4033-7

Oligomerization in detergent micelles
While systems such as GpA exhibit strong association under the conditions of SDS-PAGE, most lateral interactions between TMs will not survive these harsh conditions. The papers listed below describe methods that exploit the known dimerization behavior of GpA to develop new means for measuring helix-helix interactions under different detergent conditions.

"Detergents modulate dimerization, but not helicity, of the glycophorin A transmembrane domain"
LE Fisher, DM Engelman and JN Sturgis J Mol Biol (1999) 293(3), 639-51

"A method for determining transmembrane helix association and orientation in detergent micelles using small angle x-ray scattering"
Z Bu and DM Engelman Biophys J (1999) 77(2), 1064-73

"The effect of point mutations on the free energy of transmembrane alpha-helix dimerization"
KG Fleming, AL Ackerman and DM Engelman J Mol Biol (1997) 272(2), 266-75

Oligomerization assays in biological membranes
The ability to assess helix-helix interactions within biological membranes will be critical for the analysis of membrane proteins that exhibit reduced stability and loss of function in detergent environments. While qualitative measures of the extent of helix-helix interactions will suffice for many purposes, quantitation of lateral associations between TMs may be necessary to understand systems that are 'poised' for regulatory purposes. Some important advances in the development of a repertoire of in vivo assays for TM oligomerization are listed below.

"TOXCAT: A measure of transmembrane helix association
in a biological membrane"
WP Russ and DM Engelman PNAS (1999) 96, 863-868

"The dimerization motif of the glycophorin A transmembrane segment in membranes: importance of glycine residues"
B Brosig and D Langosch Protein Sci (1998) 7(4), 1052-6

"Dimerisation of the glycophorin A transmembrane segment in membranes probed with the ToxR transcription activator"
D Langosch, B Brosig, H Kolmar and HJ Fritz J Mol Biol (1996) 263(4), 525-30

"Lambda repressor N-terminal DNA-binding domain as an assay for protein transmembrane segment interactions in vivo"
JA Leeds and J Beckwith J Mol Biol (1998) 280(5), 799-810

Structure in detergent micelles
"A transmembrane helix dimer: structure and implications"
KR MacKenzie, JH Prestegard and DM Engelman Science (1997) 276, 131-133

"Leucine sidechain rotamers in a glycophorin A transmembrane peptide as revealed by three bond carbon-carbon couplings and ¹³C chemical shift"
KR MacKenzie, JH Prestegard and DM Engelman J. Biomol. NMR (1996) 7, 256-260

Structure and dimerization in artificial bilayers
"Site directed dichroism as a method for obtaining rotational and orientational constraints for oriented polymers"
IT Arkin, KR MacKenzie and AT Brünger JACS (1997) 119(38), 8973-8980

"Glycophorin A helical transmembrane domains dimerize in phospholipid bilayers: a resonance energy transfer study"
BD Adair and DM Engelman Biochemistry (1994) 33(18), 5539-44

"Sequence and structure of the membrane-associated peptide of glycophorin A"
N Challou, E Goormaghtigh, V Cabiaux, K Conrath and JM Ruysschaert Biochemistry (1994) 33(22), 6902-10

"Structure and orientation of the transmembrane domain of glycophorin A in lipid bilayers"
SO Smith, R Jonas, M Braiman and BJ Bormann Biochemistry (1994) 33(20), 6334-41

Computational methods
"A potential smoothing algorithm accurately predicts transmembrane helix packing"
RV Pappu, GR Marshall and JW Ponder Nat Struct Biol (1999) 6(1), 50-5

"Improved prediction for the structure of the dimeric transmembrane domain of glycophorin A obtained through global searching"
PD Adams, DM Engelman and AT Brünger Proteins (1996) 26(3), 257-61

"The glycophorin A transmembrane domain dimer: sequence-specific propensity for a right-handed supercoil of helices"
HR Treutlein, MA Lemmon, DM Engelman and AT Brünger Biochemistry (1992) 31(51), 12726-32