ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 6 | 6 hits

Sorting

Electronic Resource

Ultrastructure of the human erythrocyte cytoskeleton and its attachment to the membrane (1991)

Ursitti, Jeanine A. ; Pumplin, David W. ; Wade, James B. ; [et al.]

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 19 (1991), S. 227-243

add to mindlist on the mindlist

Details

ISSN: 0886-1544

Keywords: spectrin ; band 3 ; anion transporter ; membrane structure ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: We attached paraformaldehyde-fixed human erythrocyte ghosts to coated coverslips and sheared them to expose the cytoskeleton. Quick-freeze, deep-etch, rotary-replication, or tannic acid/osmium fixation and plastic embedding revealed the cytoskeleton as a dense network of intersecting straight filaments. Previous negative stain studies on spread skeletons found 5-6 spectrin tetramers intersecting at each actin oligomer, with an estimated 250 such intersections/μm2 of membrane. In contrast, we found 3-4 filaments at each intersection and ∼400 intersections/μm2 of membrane. Immunogold labeling verified that the filaments were spectrin, but their lengths (29-37 nm) were approximately one-third that of extended spectrin dimers. The length and diameter of the filaments were sufficient to accommodate spectrin dimers, but not spectrin tetraments. Our results suggest that, in situ, spectrin dimers may associations as hexamers and octamers, rather than tetramers. We present several explanations that can reconcile our observations on intact cytoskeletons with previous reports on spread material.Extracting sheared ghosts with solutions of low ionic strength removed the cytoskeleton to reveal projections from the cytoplasmic surface of the membrane. These projections contained band 3, as shown by immunogold labeling, and they aggregated to a similar extent as intramembrane particles (IMP) when the cytoskeleton was removed, suggesting a direct relationship between these structures. Quantification indicated a stoichiometry of 2 IMP for each cytoplasmic projection. Cytoplasmic projections presumably contain other proteins besides band 3 since further treatment with high ionic strength solutions extracts peripheral proteins and reduces the diameter of projections by ∼3 nm.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970190402

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Ultrastructure and immunocytochemistry of the isolated human erythrocyte membrane skeleton (1993)

Ursitti, Jeanine A. ; Wade, James B.

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 25 (1993), S. 30-42

add to mindlist on the mindlist

Details

ISSN: 0886-1544

Keywords: spectrin ; cytoskeleton ; erythrocyte ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Isolated skeletons from human erythrocyte ghosts were studied using immunogold labeling; negative staining; and quick-freeze, deep-etch, rotary replication with Pt/C (QFDERR). Isolated skeletons visualized by QFDERR were similar to the negatively stained skeletons in that the proteins spectrin, actin, and ankyrin could be easily distinguished. However, the quick-frozen skeletons had two fewer filaments (4.2 ± 0.7) at an actin junction. Immunogold labeling of skeletons with site-specific spectrin antibodies not only confirmed the designation of these filaments as spectrin molecules, but indicated that about 30% of spectrin filaments form non-actin junctions consistent with the hexameric organization of these filaments. Many of the filaments displayed a striking banding pattern indicative of underlying substructure. Isolated skeletons prepared by QFDERR also showed evidence of laterally associated spectrin filaments. These associations, as well as many hexamer junctions, are lost during negative staining. Negative staining also apparently caused ∼21% of the spectrin filaments to separate into their monomeric subunits. These results indicate that the surface tension imposed during negative staining of isolated skeletons can cause a loss of interactions normally present in the intact membrane skeleton. © 1993 Wiley-Liss, Inc.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970250105

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Quick-freeze, deep-etch replication of cells in monolayers (1990)

Pumplin, David W. ; Luther, Paul W. ; Samuelsson, Steven J. ; [et al.]

New York, NY : Wiley-Blackwell

Journal of Electron Microscopy Technique 14 (1990), S. 342-347

add to mindlist on the mindlist

Details

ISSN: 0741-0581

Keywords: Quick-freeze deep-etch rotary replication ; Cell monolayers ; Tissue culture ; Specimen preparation ; Freeze-etch artifacts ; Temperature control ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Natural Sciences in General

Notes: We have made several technical improvements for quick-freeze, deep-etch replication of monolayers of cells grown on, or attached to, glass coverslips. Cells studied include muscle cells of rat and Xenopus cultured on glass coverslips, and erythrocytes attached to coverslips coated with poly-L-lysine. We describe methods for identifying particular areas of cultures, e.g., clusters of acetylcholine receptors on muscle cells, by light microscopy and then relocating these areas after replication. For good preservation of structure by quick-freezing, it is necessary to ensure that the surface to be frozen is covered by a minimum depth of water (〈 10 μm). Insufficient or excess water left on the sample during freezing causes recognizable artifacts in its replica. We describe two ways to control the water table-one by improving visual control of water removal, the other by blowing excess water off the sample surface with a jet of nitrogen applied during its descent to the freezing block. Finally, we describe a new specimen holder that allows us to etch and replicate six samples at once with good thermal contact between the stage and samples.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jemt.1060140409

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Unknown

Mena/VASP and αII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy (2013)

Benz, Peter M ; Merkel, Carla J ; Offner, Kristin ; [et al.]

BioMed Central

In: Cell Communication and Signaling. 2013; 11(1): 56. Published 2013 Jan 01. doi: 10.1186/1478-811x-11-56.

add to mindlist on the mindlist

Details

Publication Date: 2013-01-01

Electronic ISSN: 1478-811X

Topics: Biology , Medicine

Published by BioMed Central

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER CURRENT

S·F·X

Fulltext

Unknown

The Exon 46-Encoded Sequence Is Essential for Stability of Human Erythroid α-Spectrin and Heterodimer Formation (1997)

Wilmotte, Rick ; Harper, Sandra L. ; Ursitti, Jeanine A. ; [et al.]

American Society of Hematology

In: Blood. 1997; 90(10): 4188-4196. Published 1997 Nov 15. doi: 10.1182/blood.v90.10.4188.

add to mindlist on the mindlist

Details

Publication Date: 1997-11-15

Description: Human erythroid α-spectrin alleles responsible for hereditary elliptocytosis (αHE alleles) undergo increased incorporation into red blood cell membranes when the polymorphism αLELY (LELY: Low Expression LYon) occurs in trans. The αLELY polymorphism is characterized by a mutation in exon 40 at codon 1857 (CTA → GTA, Leu → Val) and the partial (50%) skipping of exon 46, which encodes residues 2177-2182 (Wilmotte et al, J Clin Invest 91:2091, 1993). Both of these peptide sequence alterations are located within the region of the α-chain involved in initiating heterodimer assembly, and either or both mutations could potentially contribute to decreased incorporation of α-chains from the αLELY allele in heterozygotes into red blood cell membranes. These possibilities were evaluated by testing the protease resistance and in vitro binding properties of normal and mutant recombinant 4-motif α subunit peptides containing the dimer initiation region. The two forms of α spectrin produced by alternative mRNA splicing of the αLELY allele were represented by α18-211857, a peptide with the codon 1857 mutation and retaining the exon 46 encoded sequence, and α18-211857-Δ46, a peptide carrying both the 1857 codon mutation and the exon 46 deletion. The properties of these two recombinant peptides were compared with α18-21, a peptide with the normal sequence at codon 1857 and retaining the exon 46 encoded sequence. The codon 1857 mutation does not adversely affect dimer formation, but it is responsible for the increased trypsin cleavage between the αIV and αV domains that was the characteristic feature initially used to identify the αLELY (SpαV/41) polymorphism (Alloisio et al, J Clin Invest 87:2169, 1991). Deletion of the six amino acids encoded by exon 46 perturbs folding of the α21 motif, because this region of the α18-211857-Δ46 peptide is rapidly degraded and this recombinant peptide is unusually prone to self-aggregation. Exon 46 deletion reduces, but does not eliminate, dimerization. Comparison of mild trypsin proteolytic products from an αLELY homozygote and the two αLELY recombinant peptides strongly suggests that little, if any, of the 50% of the α chains from the αLELY allele that contain the exon 46 deletion are incorporated into the mature erythroid membrane. Based on the in vitro analysis of recombinant αLELY peptides, the inability of detectable amounts of exon 46− α chains to assemble into the mature membrane skeleton in vivo is probably due to a combination of decreased dimer binding affinity and increased proteolytic degradation of these mutant chains.

Print ISSN: 0006-4971

Electronic ISSN: 1528-0020

Topics: Biology , Medicine