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White SH. Fifty Years of Biophysics at the Membrane Frontier. Annu Rev Biophys 2023; 52:21-67. [PMID: 36791747 DOI: 10.1146/annurev-biophys-051622-112341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The author first describes his childhood in the South and the ways in which it fostered the values he has espoused throughout his life, his development of a keen fascination with science, and the influences that supported his progress toward higher education. His experiences in ROTC as a student, followed by two years in the US Army during the Vietnam War, honed his leadership skills. The bulk of the autobiography is a chronological journey through his scientific career, beginning with arrival at the University of California, Irvine in 1972, with an emphasis on the postdoctoral students and colleagues who have contributed substantially to each phase of his lab's progress. White's fundamental findings played a key role in the development of membrane biophysics, helping establish it as fertile ground for research. A story gradually unfolds that reveals the deeply collaborative and painstakingly executed work necessary for a successful career in science.
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Affiliation(s)
- Stephen H White
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA;
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Bieberich E. Sphingolipids and lipid rafts: Novel concepts and methods of analysis. Chem Phys Lipids 2018; 216:114-131. [PMID: 30194926 PMCID: PMC6196108 DOI: 10.1016/j.chemphyslip.2018.08.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/20/2018] [Accepted: 08/25/2018] [Indexed: 12/12/2022]
Abstract
About twenty years ago, the functional lipid raft model of the plasma membrane was published. It took into account decades of research showing that cellular membranes are not just homogenous mixtures of lipids and proteins. Lateral anisotropy leads to assembly of membrane domains with specific lipid and protein composition regulating vesicular traffic, cell polarity, and cell signaling pathways in a plethora of biological processes. However, what appeared to be a clearly defined entity of clustered raft lipids and proteins became increasingly fluid over the years, and many of the fundamental questions about biogenesis and structure of lipid rafts remained unanswered. Experimental obstacles in visualizing lipids and their interactions hampered progress in understanding just how big rafts are, where and when they are formed, and with which proteins raft lipids interact. In recent years, we have begun to answer some of these questions and sphingolipids may take center stage in re-defining the meaning and functional significance of lipid rafts. In addition to the archetypical cholesterol-sphingomyelin raft with liquid ordered (Lo) phase and the liquid-disordered (Ld) non-raft regions of cellular membranes, a third type of microdomains termed ceramide-rich platforms (CRPs) with gel-like structure has been identified. CRPs are "ceramide rafts" that may offer some fresh view on the membrane mesostructure and answer several critical questions for our understanding of lipid rafts.
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Affiliation(s)
- Erhard Bieberich
- Department of Physiology at the University of Kentucky, Lexington, KY, United States.
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Van Duijn G, Dekker J, Leunissen-Bijvelt J, Verkleij AJ, De Kruijff B. Influence of trinitrophenylation on the structure and dynamics of phosphatidylethanolamine-containing model membranes. Biochemistry 2002. [DOI: 10.1021/bi00347a022] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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McIntosh TJ. Chapter 2 Structure and Physical Properties of the Lipid Membrane. CURRENT TOPICS IN MEMBRANES 1999. [DOI: 10.1016/s0070-2161(08)61040-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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Pasternak CA, Alder GM, Bashford CL, Korchev YE, Pederzolli C, Rostovtseva TK. Membrane damage: common mechanisms of induction and prevention. FEMS MICROBIOLOGY IMMUNOLOGY 1992; 5:83-92. [PMID: 1384600 DOI: 10.1111/j.1574-6968.1992.tb05890.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Common features in the induction of pores by various agents are as follows: induction is stochastic and progressive; damage by different agents is often synergistic and limited. The prevention of membrane damage is affected by trivalent and divalent cations, by low pH, by low ionic strength and by high osmotic pressure. The inhibitory role of protons and divalent cations is considered in greater detail: pore-forming agents can be classified into two groups: channels across planar lipid bilayers induced by the first group display voltage-sensitive, reversible inhibition by divalent cations; channels of the second group show voltage-insensitive, irreversible inhibition by divalent cations. A search for the ligands to which divalent cations and protons bind has proved elusive. Comparison with the phenomenon of 'surface conductance' through narrow apertures, that is manifest in the absence of any pore-forming agent, may prove fruitful.
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Affiliation(s)
- C A Pasternak
- Department of Cellular and Molecular Sciences, St. George's HMS, London, UK
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Seddon JM. Structure of the inverted hexagonal (HII) phase, and non-lamellar phase transitions of lipids. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1031:1-69. [PMID: 2407291 DOI: 10.1016/0304-4157(90)90002-t] [Citation(s) in RCA: 775] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- J M Seddon
- Chemistry Department, The University, Southampton, U.K
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Cervato G, Marchesini S, Viani P, Vecchio G, Omodeo-Sale F, Cestaro B. Interactions of insulin with sulfatide-containing vesicles of phosphatidylcholine at different pHs. Chem Phys Lipids 1987; 43:135-46. [PMID: 3297369 DOI: 10.1016/0009-3084(87)90032-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Positively charged insulin is described to induce aggregation of phosphatidylcholine vesicles containing 10 mol% sulfatide at acidic pH. Techniques including light-scattering, Sepharose chromatography, centrifugation, trapped volume determination, circular dichroism and fluorescence polarization, demonstrate that large amounts of negatively charged insulin remain firmly associated to the vesicles upon raising the pH to 7. This is surprising, since only trace amounts of insulin associate to the sulfatide-containing vesicles upon direct incubation at pH 7. The possible molecular explanation of the phenomenon and the relevance of these findings to the actions of insulin in vivo are discussed.
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Robertson JD. The early days of electron microscopy of nerve tissue and membranes. INTERNATIONAL REVIEW OF CYTOLOGY 1987; 100:129-201. [PMID: 3549603 DOI: 10.1016/s0074-7696(08)61700-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Maggio B, Cumar FA, Caputto R. Molecular behaviour of glycosphingolipids in interfaces. Possible participation in some properties of nerve membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 650:69-87. [PMID: 7037053 DOI: 10.1016/0304-4157(81)90001-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Liska B, Janisch R. Membrane structures of Acholeplasma laidlawii and its virus. Folia Microbiol (Praha) 1981; 26:287-93. [PMID: 7286852 DOI: 10.1007/bf02927253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The main types of ultrastructures found in the freeze-fracture faces of Acholeplasma laidlawii S 2 and its virus MV-Lg-L 172 were (1) particles 7-19 nm in diameter, mostly located in the convex cytoplasmic fracture faces. (2) small bulges or aggregates, 13-25 nm in diameter, which occupied only limited areas of both inner and outer fracture faces of some mycoplasmas, (3) numerous tiny grains and/or spikes 2-6 nm in diameter, protruding from a finely structured background, especially in the outer concave mycoplasmal fracture faces, and (4) linear structures, most probably fibrils and thicker filaments, both in the fracture faces and around mycoplasmas and viruses and connected with them. There was a high degree of structural similarity between mycoplasmal and viral membranes: no obvious significant difference was found.
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Cullis PR, de Kruijff B. Lipid polymorphism and the functional roles of lipids in biological membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 559:399-420. [PMID: 391283 DOI: 10.1016/0304-4157(79)90012-1] [Citation(s) in RCA: 1312] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Dandrifosse G. [Secretion of digestive enzymes in vertebrates]. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1977; 85:641-848. [PMID: 74987 DOI: 10.3109/13813457709079437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Breisblatt W, Ohki S. Fusion in phospholipid spherical membranes. II. Effect of cholesterol, divalent ions and pH. J Membr Biol 1976; 29:127-46. [PMID: 10444 DOI: 10.1007/bf01868956] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Effect of cholesterol, divalent ions and pH on spherical bilayer membrane fusion was studied as a function of increasing temperature. Spherical bilayer membranes were composed of natural [phosphatidylcholine (PC) and phosphatidylserine (PS)] as well as synthetic (dipalmitoyl-PC, dimyristoyl-PC and dioleoyl-PC) phospholipids. Incorporation of cholesterol into the membrane (33% by weight) suppressed the fusion temperature and also greatly reduced the percentage of membrane fusion. The presence of 1 mM divalent ions (Ca++, Mg++ or Mn++) on both sides or one side of the PC membrane did not affect appreciably its fusion characteristic with temperature, but the PS membrane fusion with temperature was greatly enhanced by the presence of divalent ions. The variation of pH of the environmental solution in the range of 5.5 approximately 7.0 did not affect the membrane fusion characteristic. However, at pH 8.5, the fusion with respect to temperature was shifted toward the lower temperature by approximately 3degreesC for PC and PS membranes, and at pH 3.0 the opposite situation was observed as the fusion temperature was increased by 6degreesC for PS membranes and by 4degreesC for PC membranes The results seem to indicate that membrane fluidity and structural instability in the bilayer are important for membrane fusion to occur.
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Bretag AH, Davis BR, Kerr DI. Potassium conductance models related to an interactive subunit membrane. J Membr Biol 1974; 16:363-80. [PMID: 4838003 DOI: 10.1007/bf01872424] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Taylor JA, Mingins J, Pethica BA, Tan BY, Jackson CM. Phase changes and mosaic formation in single and mixed phospholipid monolayers at the oil--water interface. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 323:157-60. [PMID: 4751243 DOI: 10.1016/0005-2736(73)90439-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Hax WM, van Venrooij GE, Denier van der Gon JJ, Elbers PF. Cell communication induced by lysolecithin. J Membr Biol 1973; 13:61-78. [PMID: 4796219 DOI: 10.1007/bf01868220] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
The arrangement of lipids and some proteins in the erythrocyte membrane has been discussed. The conclusions from this are listed here as a set of general guidelines for the structure of membranes of higher organisms: some of these rules may be wrong. But at this stage it seems useful to sharpen our thoughts in this way and thereby focus attention on various specific points. 1) The basis of a membrane is a lipid bilayer with (i) choline phospholipids and glycolipids in the external half and (ii) amino (and possibly some choline) phospholipids in the cytoplasmic half. There is effectively no lipid exchange across the bilayer (unless enzymatically catalyzed) (68). 2) Some proteins extend across the bilayer. Where this is so, they will in general have carbohydrate on their surface remote from the cytoplasm. This carbohydrate may prevent the protein diffusing out of the membrane into the cytoplasm; it acts as a lock on the protein. 3) Just as lipids do not flip-flop, proteins do not rotate across the membrane. Lateral motion or rotation of lipids and proteins in the plane of the bilayer may be expected. 4) Most membrane protein is associated with the inner, cytoplasmic, urface of the membrane. Proteins are not usually associated exclusively with the outer half of the lipid bilayer. 5) Membrane proteins are a special class of cytoplasmic proteins, not of secreted proteins.
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Bolis L. The red blood cell membrane as a model for targets of drug action. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1973; 17:59-107. [PMID: 4593393 DOI: 10.1007/978-3-0348-7084-9_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Grout BW, Willison JH, Cocking EC. Interactions at the surface of plant cell protoplasts; an electrophoretic and freeze-etch study. JOURNAL OF BIOENERGETICS 1973; 4:311-28. [PMID: 4717528 DOI: 10.1007/bf01516064] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
This chapter discusses lipids in viruses. Lipid forms an integral part of many viruses and exists either in the form of a continuous envelope or in lipoprotein complexes that surround a nucleoprotein core or helix. In general, the envelope can be described as a molecular container for the genetic material of the virus. Viruses are obligate intracellular parasites and are not known to carry genetic coding for enzymes involved in lipid synthesis. Hence, they generally contain the same classes of lipid as are found in the host cell or their membrane of assembly. Lipids make up 20–35% by weight of most viruses; however, there are exceptions such as vaccinia virus, which has only 5% lipid despite having a complex multimembrane envelope structure. Naked herpesvirus capsids closely resemble non-lipid-containing viruses such as adenovirus or polyoma virus, which are also assembled in the nucleus but show full infectivity without any envelope. Both naked and enveloped herpesvirus particles are found in infected cells; however, only enveloped particles are found in extracellular fluids.
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Roland JC. The relationship between the plasmalemma and plant cell wall. INTERNATIONAL REVIEW OF CYTOLOGY 1973; 36:45-92. [PMID: 4128634 DOI: 10.1016/s0074-7696(08)60215-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Higgins JA, Florendo NT, Barrnett RJ. Localization of cholesterol in membranes of erythrocyte ghosts. JOURNAL OF ULTRASTRUCTURE RESEARCH 1973; 42:66-81. [PMID: 4119258 DOI: 10.1016/s0022-5320(73)80006-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Hsia JC, Chen WL, Long RA, Wong LT, Kalow W. Existence of phospholipid bilayer structure in the inner membrane of mitochondria. Proc Natl Acad Sci U S A 1972; 69:3412-5. [PMID: 4343971 PMCID: PMC389782 DOI: 10.1073/pnas.69.11.3412] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The presence of ordered phospholipid lamellar structure in inner membranes of mitochondria was detected with the use of a spin-labeled 2,4-dinitrophenol. A phospholipid bilayer may be an important structural and functional component of the inner mitochondrial membrane.
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Gurd JW, Evans WH, Perkins HR. The distribution of surface antigens during fractionation of mouse liver plasma membranes. Biochem J 1972; 130:271-80. [PMID: 4120434 PMCID: PMC1174324 DOI: 10.1042/bj1300271] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
1. Antiserum to purified mouse liver plasma membranes was prepared and the partially purified gamma-globulin antibody fraction was iodinated with (125)I. The reaction of the (125)I-labelled gamma-globulin antibody with isolated mouse liver plasma membranes was studied. 2. The gammaglobulin antibody bound specifically to mouse liver plasma membranes and there was little reaction with mouse liver intracellular membranes or with surface-membrane fractions from either rat liver or pig lymphocytes. 3. ;Light' and ;heavy' mouse liver plasma-membrane subfractions bound similar amounts of gamma-globulin antibody, and this is consistent with a surface origin for the light fraction. 5. Plasma membranes were fractionated by sequential extraction with 50mm-NaHCO(3)-Na(2)CO(3) buffer, pH10.2, containing 10mm-EDTA and aq. 33% (v/v) pyridine. The alkali-soluble and -insoluble fractions and the pyridine-soluble and -insoluble fractions all reacted with the antiserum, and the cross-reactivity among the various fractions and with the total plasma membranes was investigated. 5. The results are discussed in terms of the arrangement of the antigenic determinants within the membrane.
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Gledhill BL, Sawicki W, Croce CM, Koprowski H. DNA synthesis in rabbit spermatozoa after treatment with lysolecithin and fusion with somatic cells. Exp Cell Res 1972; 73:33-40. [PMID: 4113944 DOI: 10.1016/0014-4827(72)90098-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Vanderkooi JM, Chance B. Temperature sensitivity of fluorescence probes in the presence of model membranes and mitochondria. FEBS Lett 1972; 22:23-26. [PMID: 11946551 DOI: 10.1016/0014-5793(72)80209-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- J M. Vanderkooi
- Department of Biophysics and Physical Biochemistry, Johnson Research Foundation, University of Pennsylvania, 19104, Philadelphia, Pennsylvania, USA
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Schwartz A, Lindenmayer GE, Allen JC. The Na+, K+-ATPase Membrane Transport System: Importance in Cellular Function. CURRENT TOPICS IN MEMBRANES AND TRANSPORT 1972. [DOI: 10.1016/s0070-2161(08)61057-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Vanderkooi JM, Martonosi A. Sarcoplasmic reticulum. XVI. The permeability of phosphatidyl choline vesicles for calcium. Arch Biochem Biophys 1971; 147:632-46. [PMID: 5167533 DOI: 10.1016/0003-9861(71)90422-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Abstract
1. A simple two-phase chloroform-aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of (125)I-labelled insulin in this system was determined after incubation at 37 degrees C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized (125)I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin-phospholipid or insulin-amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin-phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [(14)C]glucose between the two phases as a monitor of phospholipid-insulin interactions. The ability of phospholipids to solubilize [(14)C]glucose in chloroform increased in the order phosphatidylcholine<sphingomyelin<phosphatidylethanolamine<phosphatidic acid. Insulin decreased the [(14)C]glucose solubilized by phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, but not by sphingomyelin. 5. The significance of these results and the molecular requirements for the formation of insulin-phospholipid complexes in chloroform are discussed.
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Wilkins MH, Blaurock AE, Engelman DM. Bilayer structure in membranes. NATURE: NEW BIOLOGY 1971; 230:72-6. [PMID: 5279041 DOI: 10.1038/newbio230072a0] [Citation(s) in RCA: 202] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Structure of Membranes and Role of Lipids Therein1 1Contribution No. 358, Animal Research Institute. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/b978-0-12-024909-1.50011-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Molecular Architecture of the Mitochondrion. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/s0070-2161(08)60033-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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The ultrastructure of plasmodesmata. PROTOPLASMA 1971; 72:315-323. [PMCID: PMC7102135 DOI: 10.1007/bf01279056] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/1970] [Revised: 12/21/1970] [Indexed: 05/18/2023]
Abstract
It is suggested that the central strand which traverses plasmodesmata is in open continuity with the endoplasmic reticulum of adjacent cells, and that this strand (desmotubule) represents a modulation of a normal ER membrane so that it comprises solely spherical protein subunits. This concept is used to illustrate how plasmodesmata could form a median nodule or anastomosing central strands. The implications of this model in relation to current theories of symplasmic transport are discussed, and the possibility for further experimental work is outlined.
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Schulze B, Kaffarnik H. [Biochemical bases of disturbed interactions between carbohydrate and fat metabolism in diabetes mellitus]. KLINISCHE WOCHENSCHRIFT 1970; 48:1147-57. [PMID: 4249838 DOI: 10.1007/bf01486632] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abercrombie M, Heaysman JE, Pegrum SM. The locomotion of fibroblasts in culture. 3. Movements of particles on the dorsal surface of the leading lamella. Exp Cell Res 1970; 62:389-98. [PMID: 5531377 DOI: 10.1016/0014-4827(70)90570-7] [Citation(s) in RCA: 237] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Cass A, Finkelstein A, Krespi V. The ion permeability induced in thin lipid membranes by the polyene antibiotics nystatin and amphotericin B. J Gen Physiol 1970; 56:100-24. [PMID: 5514157 PMCID: PMC2225864 DOI: 10.1085/jgp.56.1.100] [Citation(s) in RCA: 227] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Characteristics of nystatin and amphotericin B action on thin (<100 A) lipid membranes are: (a) micromolar amounts increase membrane conductance from 10(-8) to over 10(-2) Omega(-1) cm(-2); (b) such membranes are (non-ideally) anion selective and discriminate among anions on the basis of size; (c) membrane sterol is required for action; (d) antibiotic presence on both sides of membrane strongly favors action; (e) conductance is proportional to a large power of antibiotic concentration; (f) conductance decreases approximately 10(4) times for a 10 degrees C temperature rise; (g) kinetics of antibiotic action are also very temperature sensitive; (h) ion selectivity is pH independent between 3 and 10, but (i) activity is reversibly lost at high pH; (j) methyl ester derivatives are fully active; N-acetyl and N-succinyl derivatives are inactive; (k) current-voltage characteristic is nonlinear when membrane separates nonidentical salt solutions. These characteristics are contrasted with those of valinomycin. Observations (a)-(g) suggest that aggregates of polyene and sterol from opposite sides of the membrane interact to create aqueous pores; these pores are not static, but break up (melt) and reform continuously. Mechanism of anion selectivity is obscure. Observations (h)-(j) suggest-NH(3) (+) is important for activity; it is probably not responsible for selectivity, particularly since four polyene antibiotics, each containing two-NH(3) (+) groups, induce ideal cation selectivity. Possibly the many hydroxyl groups in nystatin and amphotericin B are responsible for anion selectivity. The effects of polyene antibiotics on thin lipid membranes are consistent with their action on biological membranes.
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Gram TE, Gillette JR. The kinetics of 32P incorporation into the phospholipids of hepatic rough and smooth microsomal membranes of male and female rats. Arch Biochem Biophys 1970; 138:199-207. [PMID: 4315692 DOI: 10.1016/0003-9861(70)90299-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Affiliation(s)
- J I. Howell
- Department of Biochemistry, Royal Free Hospital School of Medicine, University of London, WC1, London, England
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