scholarly journals Structural membrane proteins and loosely associated proteins of the sarcoplasmic reticulum

1974 ◽  
Vol 139 (3) ◽  
pp. 509-513 ◽  
Author(s):  
A. Margreth ◽  
U. Carraro ◽  
G. Salviati
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Membrane Proteins ◽  
Osmotic Shock ◽  
Protein Composition ◽  
Polyacrylamide Gels ◽  
Associated Proteins

The protein composition of sarcoplasmic-reticulum vesicles, either unpurified or after fractionation on sucrose gradients, and with or without previous osmotic shock and sonication, was investigated by electrophoresis in acid polyacrylamide gels. The pattern of release of loosely bound proteins is discussed with respect to their localization in the interior of the vesicles.

scholarly journals Cell-surface remodelling during mammalian erythropoiesis

1982 ◽  
Vol 208 (1) ◽  
pp. 239-242 ◽  
Author(s):  
D C Wraith ◽  
C J Chesterton
Keyword(s):  
Surface Modification ◽  
Membrane Proteins ◽  
Cell Surface ◽  
Protein Composition ◽  
Surface Protein ◽  
Current Evidence ◽  
Cell Surface Protein ◽  
Erythroid Cells ◽  
Selective Loss ◽  
Before And After

Current evidence suggests that the major cell-surface modification occurring during mammalian erythropoiesis could be generated by two separate mechanisms: either selective loss of membrane proteins during enucleation or endocytosis at the subsequent reticulocyte and erythrocyte stages. The former idea was tested by collecting developing rabbit erythroid cells before and after the enucleation step and comparing their cell-surface protein composition via radiolabelling and electrophoresis. Few changes were observed. Our data thus lend support to the endocytosis mechanism.

scholarly journals Differential impact of mitochondrial positioning on mitochondrial Ca2+ uptake and Ca2+ spark suppression in skeletal muscle

2011 ◽  
Vol 301 (5) ◽  
pp. C1128-C1139 ◽  
Author(s):  
Ann E. Rossi ◽  
Simona Boncompagni ◽  
Lan Wei ◽  
Feliciano Protasi ◽  
Robert T. Dirksen
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Osmotic Shock ◽  
Progressive Increase ◽  
Tetanic Stimulation ◽  
Differential Impact ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Activity Dependent ◽  
Old Mice

Muscle contraction requires ATP and Ca2+ and, thus, is under direct control of mitochondria and the sarcoplasmic reticulum. During postnatal skeletal muscle maturation, the mitochondrial network exhibits a shift from a longitudinal (“longitudinal mitochondria”) to a mostly transversal orientation as a result of a progressive increase in mitochondrial association with Ca2+ release units (CRUs) or triads (“triadic mitochondria”). To determine the physiological implications of this shift in mitochondrial disposition, we used confocal microscopy to monitor activity-dependent changes in myoplasmic (fluo 4) and mitochondrial (rhod 2) Ca2+ in single flexor digitorum brevis (FDB) fibers from 1- to 4-mo-old mice. A robust and sustained Ca2+ accumulation in triadic mitochondria was triggered by repetitive tetanic stimulation (500 ms, 100 Hz, every 2.5 s) in FDB fibers from 4-mo-old mice. Specifically, mitochondrial rhod 2 fluorescence increased 272 ± 39% after a single tetanus and 412 ± 45% after five tetani and decayed slowly over 10 min following the final tetanus. Similar results were observed in fibers expressing mitochondrial pericam, a mitochondrial-targeted ratiometric Ca2+ indicator. Interestingly, sustained mitochondrial Ca2+ uptake following repetitive tetanic stimulation was similar for triadic and longitudinal mitochondria in FDB fibers from 1-mo-old mice, and both mitochondrial populations were found by electron microscopy to be continuous and structurally tethered to the sarcoplasmic reticulum. Conversely, the frequency of osmotic shock-induced Ca2+ sparks per CRU density decreased threefold (from 3.6 ± 0.2 to 1.2 ± 0.1 events·CRU−1·min−1·100 μm−2) during postnatal development in direct linear correspondence ( r2 = 0.95) to an increase in mitochondrion-CRU pairing. Together, these results indicate that mitochondrion-CRU association promotes Ca2+ spark suppression but does not significantly impact mitochondrial Ca2+ uptake.

The fine structure and the protein composition of γ phage of Bacillus anthracis

1975 ◽  
Vol 21 (11) ◽  
pp. 1889-1892 ◽  
Author(s):  
Takashi Watanabe ◽  
Akinori Morimoto ◽  
Toshiro Shiomi
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Bacillus Anthracis ◽  
Protein Composition ◽  
Staining Technique ◽  
Negative Staining ◽  
Polyacrylamide Gels ◽  
Long Tail

The fine structure of γ phage of Bacillus anthracis was studied by electron microscopy with a negative-staining technique. The phage has a hexagonal head and a long tail without a sheath. By electrophoresis on polyacrylamide gels, the proteins of the phage particles are separate into 10 polypeptides with moleclar weights ranging from 140 000 to 12 000.

Outer Membrane Protein Composition in Disease Isolates of Haemophilus influenzae : Pathogenic and Epidemiological Implications

1980 ◽  
Vol 30 (3) ◽  
pp. 709-717
Author(s):  
Marilyn R. Loeb ◽  
David H. Smith
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Haemophilus Influenzae ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Protein Composition ◽  
The Other ◽  
Major Protein ◽  
Single Strain

The outer membrane protein composition of 50 disease isolates of Haemophilus influenzae has been determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All strains, including 28 strains of serotype b , one strain each of serotypes a, c, d, e , and f , and 17 untypable strains, had an outer membrane protein composition typical of gram-negative bacteria, i.e., these membranes contained two to three dozen proteins with four to six proteins accounting for most of their protein content. Variation in the mobility of these major outer membrane proteins from strain to strain was common but not universal; the observed patterns provided useful data and new insight into the epidemiology of type b disease. The basic findings can be summarized as follows: (i) All 50 strains possessed three proteins (one minor and two major) each having identical mobilities. The other proteins, both major and minor, varied in mobility. (ii) All type b strains possessed a fourth (major) protein of identical mobility. (iii) The 28 type b strains, on the basis of the mobility of the six major outer membrane proteins, could be divided into eight subtypes. Of all the other strains examined, both typable and untypable, only the serotype a strain belonged to one of these subtypes. (iv) The untypable strains showed considerable variation in the mobilities of their major outer membrane proteins. Of these 17 strains, 13 had an additional major outer membrane protein not present in encapsulated strains. (v) The outer membrane protein composition of a single strain remained unchanged after many passages on solid media, but varied with the growth phase. (vi) The outer membrane protein composition of isolates obtained from nine patients during an epidemic of type b meningitis varied, indicating that a single strain was not responsible for the epidemic. At least five different strains were responsible for these nine cases. (vii) Identical outer membrane protein compositions were observed in the following: in a type b strain and a mutant of this strain deficient in capsule production, indicating that the level of capsule synthesis is not obviously related to outer membrane protein composition; in type b strains isolated from different anatomic sites of patients acutely ill with meningitis, indicating that the strain associated with bacteremia is the same as that isolated from the cerebrospinal fluid; in type b strains isolated from siblings who contracted meningitis at about the same time, indicating infection with the same strain; and in type b strains isolated from the initial and repeat infection of a single patient, suggesting that reinfection was due to the same strain.

scholarly journals The Fusion of Lipid and DNA Nanotechnology

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1001 ◽  
Author(s):  
Es Darley ◽  
Jasleen Kaur Daljit Singh ◽  
Natalie A. Surace ◽  
Shelley F. J. Wickham ◽  
Matthew A. B. Baker
Keyword(s):  
Membrane Proteins ◽  
Lipid Membranes ◽  
Dna Nanotechnology ◽  
Bilayer Membrane ◽  
Diverse Range ◽  
Impermeable Barrier ◽  
Self Assembling ◽  
Associated Proteins ◽  
Fundamental Biological Process

Lipid membranes form the boundary of many biological compartments, including organelles and cells. Consisting of two leaflets of amphipathic molecules, the bilayer membrane forms an impermeable barrier to ions and small molecules. Controlled transport of molecules across lipid membranes is a fundamental biological process that is facilitated by a diverse range of membrane proteins, including ion-channels and pores. However, biological membranes and their associated proteins are challenging to experimentally characterize. These challenges have motivated recent advances in nanotechnology towards building and manipulating synthetic lipid systems. Liposomes—aqueous droplets enclosed by a bilayer membrane—can be synthesised in vitro and used as a synthetic model for the cell membrane. In DNA nanotechnology, DNA is used as programmable building material for self-assembling biocompatible nanostructures. DNA nanostructures can be functionalised with hydrophobic chemical modifications, which bind to or bridge lipid membranes. Here, we review approaches that combine techniques from lipid and DNA nanotechnology to engineer the topography, permeability, and surface interactions of membranes, and to direct the fusion and formation of liposomes. These approaches have been used to study the properties of membrane proteins, to build biosensors, and as a pathway towards assembling synthetic multicellular systems.

The protein composition of gluten extracted from different wheats

1963 ◽  
Vol 3 (9) ◽  
pp. 85 ◽  
Author(s):  
JW Lee ◽  
CW Wrigley
Keyword(s):  
Carboxymethyl Cellulose ◽  
Protein Profile ◽  
Protein Composition ◽  
Tetraploid Species ◽  
Protein Profiles ◽  
Polyacrylamide Gels ◽  
Wheat Varieties ◽  
Gluten Proteins ◽  
Baking Quality ◽  
Triticum Species

The gluten proteins from eight commercial wheat varieties and four tetraploid Triticum species were separated by chromatograph on carboxymethyl-cellulose and by electrophoresis on polyacrylamide gels. There are obvious differences in the protein profiles of many of the commercial wheat varieties. Furthermore, the tetraploid species differ in many respects from the T. vulgare varieties. The possible relationship between baking quality and protein profile is discussed.

scholarly journals Aldolase potentiates DIDS activation of the ryanodine receptor in rabbit skeletal sarcoplasmic reticulum

2006 ◽  
Vol 399 (2) ◽  
pp. 325-333 ◽  
Author(s):  
In-Ra Seo ◽  
Sang Hyun Moh ◽  
Eun Hui Lee ◽  
Gerhard Meissner ◽  
Do Han Kim
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Column Chromatography ◽  
Anion Channel ◽  
Affinity Column ◽  
Open Probability ◽  
Release Channel ◽  
Affinity Column Chromatography ◽  
Lifetime Analysis ◽  
Associated Proteins

DIDS (4,4′-di-isothiocyanostilbene-2,2′-disulfonate), an anion channel blocker, triggers Ca2+ release from skeletal muscle SR (sarcoplasmic reticulum). The present study characterized the effects of DIDS on rabbit skeletal single Ca2+-release channel/RyR1 (ryanodine receptor type 1) incorporated into a planar lipid bilayer. When junctional SR vesicles were used for channel incorporation (native RyR1), DIDS increased the mean Po (open probability) of RyR1 without affecting unitary conductance when Cs+ was used as the charge carrier. Lifetime analysis of single RyR1 activities showed that 10 μM DIDS induced reversible long-lived open events (Po=0.451±0.038) in the presence of 10 μM Ca2+, due mainly to a new third component for both open and closed time constants. However, when purified RyR1 was examined in the same condition, 10 μM DIDS became considerably less potent (Po=0.206±0.025), although the caffeine response was similar between native and purified RyR1. Hence we postulated that a DIDS-binding protein, essential for the DIDS sensitivity of RyR1, was lost during RyR1 purification. DIDS-affinity column chromatography of solubilized junctional SR, and MALDI–TOF (matrix-assisted laser-desorption ionization–time-of-flight) MS analysis of the affinity-column-associated proteins, identified four major DIDS-binding proteins in the SR fraction. Among them, aldolase was the only protein that greatly potentiated DIDS sensitivity. The association between RyR1 and aldolase was further confirmed by co-immunoprecipitation and aldolase-affinity batch-column chromatography. Taken together, we conclude that aldolase is physically associated with RyR1 and could confer a considerable potentiation of the DIDS effect on RyR1.

scholarly journals Large-scale quantitative LC-MS/MS analysis of detergent-resistant membrane proteins from rat renal collecting duct

2008 ◽  
Vol 295 (3) ◽  
pp. C661-C678 ◽  
Author(s):  
Ming-Jiun Yu ◽  
Trairak Pisitkun ◽  
Guanghui Wang ◽  
Juan F. Aranda ◽  
Patricia A. Gonzales ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Large Scale ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Apical Region ◽  
Annexin 2 ◽  
Associated Proteins ◽  
Medullary Collecting Duct ◽  
Renal Collecting Duct

In the renal collecting duct, vasopressin controls transport of water and solutes via regulation of membrane transporters such as aquaporin-2 (AQP2) and the epithelial urea transporter UT-A. To discover proteins potentially involved in vasopressin action in rat kidney collecting ducts, we enriched membrane “raft” proteins by harvesting detergent-resistant membranes (DRMs) of the inner medullary collecting duct (IMCD) cells. Proteins were identified and quantified with LC-MS/MS. A total of 814 proteins were identified in the DRM fractions. Of these, 186, including several characteristic raft proteins, were enriched in the DRMs. Immunoblotting confirmed DRM enrichment of representative proteins. Immunofluorescence confocal microscopy of rat IMCDs with antibodies to DRM proteins demonstrated heterogeneity of raft subdomains: MAL2 (apical region), RalA (predominant basolateral labeling), caveolin-2 (punctate labeling distributed throughout the cells), and flotillin-1 (discrete labeling of large intracellular structures). The DRM proteome included GPI-anchored, doubly acylated, singly acylated, cholesterol-binding, and integral membrane proteins (IMPs). The IMPs were, on average, much smaller and more hydrophobic than IMPs identified in non-DRM-enriched IMCD. The content of serine 256-phosphorylated AQP2 was greater in DRM than in non-DRM fractions. Vasopressin did not change the DRM-to-non-DRM ratio of most proteins, whether quantified by tandem mass spectrometry (LC-MS/MS, n = 22) or immunoblotting ( n = 6). However, Rab7 and annexin-2 showed small increases in the DRM fraction in response to vasopressin. In accord with the long-term goal of creating a systems-level analysis of transport regulation, this study has identified a large number of membrane-associated proteins expressed in the IMCD that have potential roles in vasopressin action.

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