title: Diffusion of glycophorin A in human erythrocytes.
abstract: Several lines of evidence suggest that glycophorin A (GPA) interacts with band 3 in human erythrocyte membranes including: i) the existence of an epitope shared between band 3 and GPA in the Wright b blood group antigen, ii) the fact that antibodies to GPA inhibit the diffusion of band 3, iii) the observation that expression of GPA facilitates trafficking of band 3 from the endoplasmic reticulum to the plasma membrane, and iv) the observation that GPA is diminished in band 3 null erythrocytes. Surprisingly, there is also evidence that GPA does not interact with band 3, including data showing that: i) band 3 diffusion increases upon erythrocyte deoxygenation whereas GPA diffusion does not, ii) band 3 diffusion is greatly restricted in erythrocytes containing the Southeast Asian Ovalocytosis mutation whereas GPA diffusion is not, and iii) most anti-GPA or anti-band 3 antibodies do not co-immunoprecipitate both proteins. To try to resolve these apparently conflicting observations, we have selectively labeled band 3 and GPA with fluorescent quantum dots in intact erythrocytes and followed their diffusion by single particle tracking. We report here that band 3 and GPA display somewhat similar macroscopic and microscopic diffusion coefficients in unmodified cells, however perturbations of band 3 diffusion do not cause perturbations of GPA diffusion. Taken together the collective data to date suggest that while weak interactions between GPA and band 3 undoubtedly exist, GPA and band 3 must have separate interactions in the membrane that control their lateral mobility.
authors: Department of Chemistry, Purdue University, West Lafayette, IN 47907, United States.
authors: Katie
authors: K
authors: Giger
authors: INSERM, UMR_S1134, Laboratory of Excellence GR-Ex, Université Paris-Diderot, Institut National de la Transfusion Sanguine, 75015 Paris, France.
authors: Ibrahim
authors: I
authors: Habib
authors: Department of Physics, Purdue University, West Lafayette, IN 47907, United States.
authors: Ken
authors: K
authors: Ritchie
authors: Department of Chemistry, Purdue University, West Lafayette, IN 47907, United States. Electronic address: plow@purdue.edu.
authors: Philip S
authors: PS
authors: Low
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001710:Biotin / Q000737:chemistry; D019921:Biotinylation; D002162:Camelus; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D005453:Fluorescence; D015870:Gene Expression; D006021:Glycophorins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D057054:Molecular Imaging; D015335:Molecular Probes / Q000737:chemistry; D021381:Protein Transport; D045663:Quantum Dots / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D061905:Single-Domain Antibodies / Q000096:biosynthesis / Q000737:chemistry
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D006021:Glycophorins; D015335:Molecular Probes; D011994:Recombinant Proteins; C454201:SLC4A1 protein, human; D061905:Single-Domain Antibodies; D001710:Biotin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
keywords: Band 3; Erythrocyte membrane structure; Glycophorin A; Single particle tracking; V(H)H