Vol. 1 No. 1 March 1996

Volume 1 (1996) pp i-3
Title PROBLEMS AND PROSPECTS IN THE RESEARCH OF RED CELL SKELETAL PROTEINS
Authors Pierre Boivin
Abstract  
Address and Contact Information Inserm U 409 et Service d'Hematologie Clinique, Hopital Beaujon, 92118 Clichy, France
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Volume 1 (1996) pp 3-14
Title DO SHAPE TRANSFORMATIONS IN ERYTHROCYTES REFLECT THE FLIP RATE OF AMPHIPHILIC COMPOUNDS?
Authors H.Hagerstrand, M. Bobrowska-Hagerstrand and B. Isomaa
Abstract It has been shown that the time course of echinocyte to discocyte transformation caused by exogenous phospholipids is an accurate measure of the flip rate of the phospholipids in the lipid bilayer. In order to explore whether shape changes in erythrocytes are indicative of flip rates of water-soluble amphiphiles, the time course of shape changes caused by a large number of amphiphiles was studied. In case of amphiphiles inducing echinocyte to discocyte or discocyte to stomatocyte transformation it is proposed that the time course of shape transformation may be indicative of the flip rate of the amphiphiles. The relevance of using shape changes in erythrocytes as a tool to estimate flip rates of amphiphiles is discussed.
Address and Contact Information Department of Biology Abo Akademi University, Biocity SF-20520, Abo/Turku, Finland
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Volume 1 (1996) pp 17-23
Title INTERACTIONS OF ANNEXINS IV AND VI WITH ERYTHROCYTE MEMBRANE IN THE PRESENCE OF CA2+. A BIOCHEMICAL AND ELECTRON MICROSCOPY STUDY
Authors J. Bandorowicz-Pikula and A. Sobota
Abstract Annexins IV and VI were found to interact with human erythrocyte membrane in a calcium-dependent manner. Chemical and enzymatic modification of the membrane constituents pointed to phosphatidylserine as a target membrane molecule responsible for the interaction of the annexin/Ca complexes with the membrane. The membrane-associated annexins were shown to form clusters reflecting , perhaps, the presence of PS microdomains in a lateral plane of membrane.
Address and Contact Information Department of Cell Biology Nencki Institute of Experimental Biology 3 Pasteur Str., 02-093 Warsaw, Poland
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Volume 1 (1996) pp 25-34
Title BRAIN SPECTRIN AND FRIENDS
Authors B. M. Riederer1, E.S. Wintergerst2, E. Valcourt3, A. Routtenberg3
Abstract Brain spectrin (fodrin, calspectin), is an actin binding protein, and composed of two alpha and two beta subunits which combine by head-to-head interaction to a heterotetramere. Together with other proteins it forms a proteinaceous meshwork underlying the cytoplasmic surface of the plasma membrane. In the mammalian brain, three forms of spectrin were identified , an axonal, a somatodendritic and a astroglial one. A subcellular localization at the electron microscopic-level suggest that these forms are not only attached to membranes but expand into the cytoplasm. It was shown that they differ in their subcellular distribution, and their temporal appearance during postnatal brain development. The subplasmalemmal cytoskeleton is composed of brain spectrin and a variety of proteins such as actin and calmodulin, and we discuss here two additional proteins, F1 and parvalbumin, which may bind to brain spectrin and may have to be included in the circle of proteins interacting with brain spectrin.
Address and Contact Information 1Institute of Anatomy , University of Lausanne , Rue du Bugnon 9, 1005 Lausanne, Switzerland
2Institut d'Histologie, Universite de Fribourg, Fribourg, Switzerland
3Northwestern University, Cresap Lab, Evanston, Il, U.S.A.
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Volume 1 (1996) pp 35-48
Title SPECTRINS-A FAMILY OF MULTIFUNCTIONAL PROTEINS WITH AFFINITY FOR CALCIUM
Authors Lars Backman
Abstract  
Address and Contact Information Department of Biochemistry Umea University S-901 87 Umea, Sweden
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Volume 1 (1996) pp 49-65
Title MOLECULAR GENETICS OF HEREDITARY SPHEROCYTOSIS
Authors J. Delaunay, N. Alloisio, L. Morle
Abstract The mechanical properties of the red cell are accounted for by its membrane and its membrane skeleton, the latter being a protein network that laminates the inner surface of the lipid bilayer. Hereditary spherocytosis (HS) is the most common of congenital hemolytic anemias. The spherocytes have a reduced lifespan due to their spheroidal shape that alters their resistance and elastic deformability. It is now established that the responsible alterations affect most often the ANK1 gene that encodes erythroid ankyrin. A noticeable HS subset is associated with a reduction of the anion exchanger 1 (AE1, or band 3), due to mutation in the corresponding gene, the EPB3 gene. Much more rarely, HS goes along with a sharp reduction, if not the absence, of protein 4.2. This stigmata results either from mutations in the DNA sequences that encode the binding site of the AE1 cytoplasmic domain for protein 4.2, or from mutations of protein 4.2 gene itself, the ELP42 gene. Mutations responsible for HS lie rarely or exceptionally in the spectrin beta or the alpha genes (SPTB and SPTA1 genes, respectively).Elucidation of new HS mutations is presently at its height. It casts light on the function of specific domains within the various proteins involved, and on the integration of protein structure and function at the cellular scale.
Address and Contact Information Laboratoire de Genetique Moleculaire Humaine CNRS, URA 1171, Institut Pasteur de Lyon, 69365 Lyon Cedex 07, France
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Volume 1 (1996) pp 67-78
Title CYTOSKELETON AND RED CELL SHAPE
Authors S.Svetina1,2, A. Iglic1,3, V. Kralj-Iglic1 and B. Zeks1,2
Abstract A view is presented on different roles which the bilayer part of the membrane and the skeleton play in establishing normal and some abnormal RBC shapes. The system is first studied at the level of elastic properties of red blood cell membrane where the latter is considered to be a trilayered structure. Then the contributions to the membrane energy are introduced which cause the membrane to become laterally inhomogeneous, in particular, the skeleton-bilayer interaction, the interaction between the membrane embedded molecules and the membrane curvature, and the distributional free energy of membrane embedded molecules. It is invoked that the role of skeleton in stabilizing red blood cell membrane is in keeping membrane integral proteins laterally distributed as homogeneously as possible.
Address and Contact Information 1Institute of Biophysics, Medical Faculty,
2Insitute J.Stefan and
3Faculty of Electrical and Computer Engineering, University of Ljubljana, SI 61000 Ljubljana, Slovenia
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Volume 1 (1996) pp 79-88
Title ISOFORM DIVERSITY AND ASSEMBLY IN NON-ERYTHROID CELLS
Authors J.C. Kim, J. McLaughlin, P.R. Stabach, C.R. Lombardo and J.S. Morrow *
Abstract Four human spectrin genes are now recognized. Two encode alpha spectrins (alpha I and alpha II), the other two encode beta spectrins (beta I and beta II). Multiple alternatively spliced transcripts have also been identified for all but alpha I spectrin, yielding a subtle but rich diversity of possible alphabeta spectrin heterodimer species in most cells. The role of these isoforms and the factors that control their assembly into the triton-insoluble cortical membrane skeleton are poorly understood. RT-PCR analysis using primers flanking regions of alternative mRNA spicing for alpha II, beta I, and beta II spectrin have been used to explore the diversity of isoform expression in cultured fibroblasts, MDCK cells, and PC12 cells. Factors that stimulate assembly or redistribution of the spectrin skeleton in these cells were also sought. Several isoforms of spectrin are expressed in each of these cell lines, and PC12 cells altered the balance of one isoform moderately in response to NGF stimulation. These three cell lines also illustrate different ways that the assembly of the cortical skeleton may be regulated. In SV40tsA58 temperature sensitive large T transformed fibroblasts, spectrin redistributes from a largely cytoplasmic distribution to focal membrane patches upon transformation; in MDCK cells, cell-cell contact initiates spectrin assembly; in PC12 cells, stimulation with growth factor (NGF) induces a redistribution of spectrin from membrane to cytoplasmic pools. Collectively, these results suggest that both cell-cell contact and growth factor mediated signalling mechanisms control the assembly and isoform composition of the spectrin cytoskeleton, and highlight the complexity of this process.
Address and Contact Information Yale University SSchool of Medicine, Department of Pathology, 310 Cedar Street, New Haven, Connecticut 06510, U.S.A.
* Corresponding author Fax 203-785-3624; E-mail: morrow@biomed.med.yale.edu.
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Volume 1 (1996) pp 89-96
Title REGULATION OF THE MECHANICAL PROPERTIES OF THE RED BLOOD CELL MEMBRANE BY PROTEIN-PROTEIN AND PROTEIN-LIPID INTERACTIONS
Authors C. DeWolf1, P. McCauley1 and J.C. Pinder2
Abstract There are two established pathways linking the membrane cytoskeleton of the red blood cell to integral proteins of the membrane. We review the characteristics of these interactions and give reasons for believing that they are insufficient to engender the exceptional stability and elastic properties that characterise the native membrane. We show that in a model system, consisting of a phospholipid monolayer, spread at the air-water interface, with the major structural protein of the membrane cytoskeleton, spectrin, added to the aqueous subphase, an energetically important interaction occurs between the protein and the lipid. This reveals itself as an area contraction, occurring at high surface pressures that do not permit penetration of the protein to the air-water interface. The interaction requires the presence in the lipid layer of the inner-leaflet component, phosphatidylserine. Binding of spectrin to the lipid is accompanied by a large increase in surface viscosity, implying that this interaction alone can exert a major effect on the mechanical properties of the membrane.
Address and Contact Information 1Department of Chemical Engineering, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BY, UK
2Medical Research Council Muscle and Cell Motility Unit, King's College, 26-29 Drury Lane, London WC2B 5RL, London, UK
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Volume 1 (1996) pp 97-104
Title INTERACTION OF SPECTRINS WITH MEMBRANE INTRINSIC DOMAIN
Authors A.F.Sikorski * and K. Bialkowska
Abstract Although interaction of red blood cell spectrin with phospholipids of the membrane bilayer was first reported more than 20 years ago its physiological significance is still a matter of dispute. In this paper we review the available data on interactions of red blood cell and nonerythroid spectrin with membrane phospholipids. The results from our laboratory indicate that ankyrin and phospholipids (particularly PE1-rich lipid domains) may, at least in part, share a binding site on erythrocyte and brain spectrin b-subunit. The physiological significance of this model is discussed.
Address and Contact Information University of Wroclaw, Department of Genetic Biochemistry, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
* Corresponding author: E-mail: afsbc@microb.uni.wroc.pl Tel. and fax: (+48 71) 25-29-30
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Volume 1 (1996) pp 105-112
Title THE MEMBRANE SKELETON IN FORMATION OF THE IRREVERSIBLY SICKLED CELL: A REVIEW
Authors S.R.Goodman
Abstract In this review we discuss the evidence in support of the concept that a posttranslational modification in beta-actin, in which a disulfide bridge is formed between cysteine 284 and cysteine 373, is the major cause of the formation of the irreversibly sickled cell (ISC). This ISC beta-actin modification caused a decreased ability of the ISC membrane skeletal proteins to disassemble, as compared to the control and reversible sickled cell (RSC) membrane skeleton, because of altered actin filament formation. The slow disassembly of the ISC membrane skeleton proteins gives a reasonable explanation for the inability of the ISC to remodel its shape. An understanding of the molecular basis of the irreversibly sickled cells formation has helped initiate a rationale for development of drugs to block ISC formation in vivo.
Address and Contact Information University of South Alabama College of Medicine, Department of Structural & Cellular Biology, USA Comprehensive Sickle Cell Center Mobile, Alabama 36688, U.S.A.
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