title: In vitro binding studies suggest a membrane-associated complex between erythroid p55, protein 4.1, and glycophorin C.
abstract: p55 is a palmitoylated peripheral membrane phosphoprotein of human erythrocytes. Primary structure of p55 includes a single copy of the SH3 motif, a COOH-terminal guanylate kinase domain, and an NH2-terminal domain of unknown function. Although the function of p55 is not known, interest in this component has been heightened by its similarity to the Drosophila tumor suppressor discs-large (dlg). In this report we provide evidence for the direct association of p55 with the NH2-terminal 30-kDa domain of protein 4.1, a key component of the erythroid membrane skeleton. In addition, p55 also binds to the cytoplasmic domain of glycophorin C, a transmembrane protein of red blood cells. We also provide evidence demonstrating the direct association of the 30-kDa domain of protein 4.1 with the cytoplasmic domain of glycophorin C. Taken together, these results suggest the existence of a novel ternary complex at the erythroid plasma membrane involving protein 4.1, p55, and glycophorin C. Since isoforms of protein 4.1, p55, and glycophorin C are present in many non-erythroid cells, the binding interactions may be prototypical of similar associations that modulate cytoskeletal-membrane linkage of broad significance.
authors.affiliation: Department of Biomedical Research, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02135.
authors.forename: S M
authors.initials: SM
authors.lastname: Marfatia
authors.forename: R A
authors.initials: RA
authors.lastname: Lue
authors.forename: D
authors.initials: D
authors.lastname: Branton
authors.forename: A H
authors.initials: AH
authors.lastname: Chishti
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D017931:DNA Primers / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000648:ultrastructure*; D006021:Glycophorins / Q000378:metabolism*; D051528:Guanylate Kinases; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009479:Neuropeptides; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; D017931:DNA Primers; D006021:Glycophorins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009479:Neuropeptides; D011993:Recombinant Fusion Proteins; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases