title: Global transformation of erythrocyte properties via engagement of an SH2-like sequence in band 3.
abstract: Src homology 2 (SH2) domains are composed of weakly conserved sequences of ∼100 aa that bind phosphotyrosines in signaling proteins and thereby mediate intra- and intermolecular protein-protein interactions. In exploring the mechanism whereby tyrosine phosphorylation of the erythrocyte anion transporter, band 3, triggers membrane destabilization, vesiculation, and fragmentation, we discovered a SH2 signature motif positioned between membrane-spanning helices 4 and 5. Evidence that this exposed cytoplasmic sequence contributes to a functional SH2-like domain is provided by observations that: (i) it contains the most conserved sequence of SH2 domains, GSFLVR; (ii) it binds the tyrosine phosphorylated cytoplasmic domain of band 3 (cdb3-PO4) with Kd= 14 nM; (iii) binding of cdb3-PO4to erythrocyte membranes is inhibited both by antibodies against the SH2 signature sequence and dephosphorylation of cdb3-PO4; (iv) label transfer experiments demonstrate the covalent transfer of photoactivatable biotin from isolated cdb3-PO4(but not cdb3) to band 3 in erythrocyte membranes; and (v) phosphorylation-induced binding of cdb3-PO4to the membrane-spanning domain of band 3 in intact cells causes global changes in membrane properties, including (i) displacement of a glycolytic enzyme complex from the membrane, (ii) inhibition of anion transport, and (iii) rupture of the band 3-ankyrin bridge connecting the spectrin-based cytoskeleton to the membrane. Because SH2-like motifs are not retrieved by normal homology searches for SH2 domains, but can be found in many tyrosine kinase-regulated transport proteins using modified search programs, we suggest that related cases of membrane transport proteins containing similar motifs are widespread in nature where they participate in regulation of cell properties.
authors.affiliation: Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907.|Department of Chemistry, Purdue University, West Lafayette, IN 47907.
authors.forename: Estela
authors.identifier: 0000-0002-3951-3925
authors.initials: E
authors.lastname: Puchulu-Campanella
authors.affiliation: Department of Oncology, University of Turin, 10126 Turin, Italy.
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Turrini
authors.affiliation: Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907.|Department of Chemistry, Purdue University, West Lafayette, IN 47907.
authors.forename: Yen-Hsing
authors.initials: YH
authors.lastname: Li
authors.affiliation: Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907; plow@purdue.edu.|Department of Chemistry, Purdue University, West Lafayette, IN 47907.
authors.forename: Philip S
authors.initials: PS
authors.lastname: Low
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry / Q000235:genetics*; D001665:Binding Sites; D017124:Conserved Sequence / Q000235:genetics; D003593:Cytoplasm / Q000737:chemistry / Q000235:genetics; D003599:Cytoskeleton / Q000737:chemistry / Q000235:genetics; D004910:Erythrocyte Membrane / Q000235:genetics / Q000378:metabolism; D004912:Erythrocytes / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics*; D017433:Protein Structure, Secondary; D018909:src Homology Domains / Q000235:genetics*
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte
keywords: SH2 domain motif; anion exchanger 1; erythrocyte glycolysis; regulation of transport proteins; tyrosine phosphorylation