Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The membrane change in En(a-) human erythrocytes. Absence of the major erythrocyte sialoglycoprotein.

ABSTRACT: We investigated the membrane of En(a-) human erythrocytes as part of a study of the structure and biochemical function of the surface glycoproteins of the mammalian cell. 2. En(a-) erythrocytes were selected because they have more extensive changes at the cell surface than any other known erythrocyte variant. 3. Our results show that in En(a-) erythrocytes: (a) the major membrane sialoglycoprotein is lacking; (b) the other major membrane-penetrating glycoprotein (band 3) has an altered electrophoretic mobility. 4. The apparent clinical normality of En(a-) cells suggests that the change in band 3 may compensate for the loss of the membrane sialoglycoproteins. It is clear that a viable erythrocyte can exist despite the absence of one of its major surface components.

SUBMITTER: Tanner MJ

PROVIDER: S-EPMC1172572 | biostudies-other | 1976 Feb

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Organization of membrane lipids and proteins in human En(a-) erythrocytes that lack the major sialoglycoprotein, glycophorin A. A spin-label study.

Project description:Membrane fluidity was studied by electron-spin-resonance techniques in human En(a-) erythrocytes that lack the major membrane sialoglycoprotein, glycophorin A. By using stearic acid spin labels with a doxyl group in the C-12 or C-15 positions, we demonstrated that the hydrophobic core in these cells was more fluid than in normal cells. Surface-located regions in isolated En(a-) membranes, when probed with stearic acid labelled in the C-5 position, appeared more stable than in normal membranes. In isolated En(a-) membranes, protein motion was decreased when probed with a nitroxide derivative of maleimide. After incubation with anti-(glycophorin A) antibodies protein motion and membrane fluidity were increased in normal membranes. This effect was observed also after spectrin depletion, which by itself increased protein motion but decreased membrane fluidity in the hydrophobic core of the membrane. The results show that membrane proteins influence the fluidity of membrane lipids.

| S-EPMC1162862 | biostudies-other

Human erythrocyte membrane sialoglycoprotein beta. The cDNA sequence suggests the absence of a cleaved N-terminal signal sequence.

Project description:We have isolated cDNA clones corresponding to the human erythrocyte membrane sialoglycoprotein beta. The clones encompass the coding region for the protein, 120 residues of the 5' non-coding region and the 3' non-coding region. The cDNA sequence suggests that sialoglycoprotein beta is not translated with the cleaved N-terminal signal sequence usual in a membrane protein of this type. Sialoglycoprotein beta or a closely related homologue is present in human kidney as well as erythroid cells.

| S-EPMC1147844 | biostudies-other

Genetic variants involving the major membrane sialoglycoprotein of human erythrocytes. Studies on erythrocytes of type Mk, Miltenberger class V and Mg.

Project description:1. Membranes from erythrocytes heterozygous for the Mk and Miltenberger Class V (Mi.V) condition and membranes from erythrocytes homozygous for the Mg condition were studied by polyacrylamide-gel electrophoresis by using the periodate/Schiff stain binding of radioiodinated lectins and labelling with lactoperoxidase. 2. Both the Mk and Mi.V conditions are associated with a decreased content of the major blood-group-MN-active sialoglycoprotein. 3. An unusual blood-group-M-active membrane component was found in Mi.V cells of appropriate genotype. No comparably component was found in Mk erythrocytes. 4. The Mg antigen appears to result from a modification of the MN-active sialoglycoprotein found in normal cells. Our results suggest that the Mg sialoglycoprotein contains fewer sialotetrasaccharides than does the normal sialglycoprotein. This may result from changes in the amino acid sequence of the protein. 5. The results are discussed in relation to differences in the antigenic properties of Mk, Mi.V and Mg cells and their possible influence on the structure of the surface of each of these cells.

| S-EPMC1186049 | biostudies-other

Abnormal carbohydrate composition of the major penetrating membrane protein of En(a-) human erythrocytes.

Project description:The major penetrating membrane glycoprotein (band 3) was isolated from En(a-) and normal human erythrocytes. The two proteins differed only in carbohydrate composition. Band 3 from En(a-) erythrocytes contained greater amounts of galactose and N-acetyl-glucosamine. The loss of the sialoglycoprotein sialotetrasaccharides in the En(a-) cell is not compensated by the appearance of these units in band 3 of En(a-) erythrocytes.

| S-EPMC1172895 | biostudies-other

A new human erythrocyte variant (Ph) containing an abnormal membrane sialoglycoprotein.

Project description:1. A new human erythrocyte variant (Ph) is described. The variant contains an unusual sialic acid-rich glycoprotein in addition to the blood-group-MN([unk])- and blood-group-Ss(delta)-active sialoglycoproteins found in normal erythrocytes. 2. The unusual component Ph has an apparent mol.wt. of 32000 on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The Ph component is not degraded during trypsin treatment of intact erythrocytes. 3. The Ph component was labelled by lacto-peroxidase-mediated radioiodination of intact erythrocytes and was found to be present in amounts approximately equimolar to alpha-sialoglycoprotein in the variant erythrocytes. 4. The Ph component had receptors for the lectins from Maclura aurantiaca (osage orange) and Triticum vulgaris (wheat-germ), but lacked a receptor for the Phaseolus vulgaris (red kidney bean) lectin, suggesting that it carries only O-linked oligosaccharides. 5. The presence of the Ph component in these erythrocytes does not correspond to any of the known blood-group-MNSs-related antigens examined. 6. We suggest that this component may be a hybrid polypeptide containing the N-terminal portion derived from normal delta-sialoglycoprotein, and the C-terminal portion from normal alpha-sialoglycoprotein, in a manner similar to the anti-Lepore haemoglobin.

| S-EPMC1161815 | biostudies-other

Labelling of the intramembranous region of the major sialoglycoprotein of human erythrocytes with a photosensitive hydrophobic probe.

Project description:Human erythrocyte membranes were incubated with the photosensitive hydrophobic reagent 1-azido-r-iodo[3H]benzene and the mixture was irradiated. The major sialoglycoprotein was then isolated and the labelled polypeptide subjected to proteolytic dissection. Characterization of the purified tryptic and chymotryptic peptides show that the probe is covalently attached only to the transmembrane region of the protein. This labelling pattern is discussed in relation to the use of such reagents for the identification of segments of membrane proteins exposed to the hydrophobic millieu of the membrane.

| S-EPMC1186623 | biostudies-other

Abnormal minor human erythrocyte membrane sialoglycoprotein (beta) in association with the rare blood-group antigen Webb (Wb).

Project description:Individuals whose erythrocytes are positive for the rare blood-group antigen Webb (Wb) have an altered form of the minor sialoglycoprotein beta (synonyms glycophorin C and glycoconnectin). This altered sialoglycoprotein beta (beta Wb) has an Mr about 2700 lower than that of normal sialoglycoprotein beta. Treatment of normal sialoglycoprotein beta with endo-beta-N-acetylglucosaminidase F decreased its Mr by about 3600, but similar treatment of sialoglycoprotein beta Wb had no effect. These results suggest the possibility that sialoglycoprotein beta Wb lacks the N-glycosidically linked oligosaccharide found on normal sialoglycoprotein beta.

| S-EPMC1152873 | biostudies-other

Absence of two membrane proteins containing extracellular thiol groups in Rhnull human erythrocytes.

Project description:Rhnull human erythrocytes lack all the antigens of the Rhesus blood-group system and are associated with mild chronic haemolytic anaemia. These erythrocytes have an abnormal shape and increased osmotic fragility. Labelling studies with the impermeant maleimide N-maleoylmethionine [35S]sulphone show that Rhnull erythrocytes lack two extracellular thiol-group-containing membrane components of apparent mol.wts. 32 000 and 34 000. Immunoprecipitation with mouse monoclonal antibody R6A (which reacts with all normal erythrocytes, but fails to react with Rhnull erythrocytes) specifically precipitates the 34 000-mol.wt. component from normal erythrocytes. Similar studies with human anti-Rh(D) serum shows that this antibody reacts with the 32 000-mol.wt. component. The results suggest that the R6A-binding polypeptide and the Rh(D) polypeptide may be involved in the maintenance of the shape and viability of the human erythrocyte.

| S-EPMC1152118 | biostudies-other

The organization of the major protein of the human erythrocyte membrane.

Project description:The enzyme lactoperoxidase was used to catalyse the radioiodination of membrane proteins in intact human erythrocytes and in erythrocyte ;ghosts'. Two major proteins of the erythrocyte membrane were isolated after iodination of these two preparations, and the peptide ;maps' of each protein so labelled were compared. Peptides from both proteins are labelled in the intact cell. In addition, further mobile peptides derived from one of the proteins are labelled only in the ;ghost' preparation. Various sealed ;ghost' preparations were also iodinated, lactoperoxidase being present only at either the cytoplasmic or extra-cellular surface of the membrane. The peptide ;maps' of protein E (the major membrane protein) labelled in each case were compared. Two discrete sets of labelled peptides were consistently found. One group is obtained when lactoperoxidase is present at the extra-cellular surface and the other group is found when the enzyme is accessible only to the cytoplasmic surface of the membrane. The results support the assumption that the organization of protein E in the membrane of the intact erythrocyte is unaltered on making erythrocyte ;ghosts'. They also confirm previous suggestions that both the sialoglycoprotein and protein E extend through the human erythrocyte membrane.

| S-EPMC1166153 | biostudies-other

Molecular cloning of human protein 4.2: a major component of the erythrocyte membrane.

Project description:Protein 4.2 (P4.2) comprises approximately 5% of the protein mass of human erythrocyte (RBC) membranes. Anemia occurs in patients with RBCs deficient in P4.2, suggesting a role for this protein in maintaining RBC stability and integrity. We now report the molecular cloning and characterization of human RBC P4.2 cDNAs. By immunoscreening a human reticulocyte cDNA library and by using the polymerase chain reaction, two cDNA sequences of 2.4 and 2.5 kilobases (kb) were obtained. These cDNAs differ only by a 90-base-pair insert in the longer isoform located three codons downstream from the putative initiation site. The 2.4- and 2.5-kb cDNAs predict proteins of approximately 77 and approximately 80 kDa, respectively, and the authenticity was confirmed by sequence identity with 46 amino acids of three cyanogen bromide-cleaved peptides of P4.2. Northern blot analysis detected a major 2.4-kb RNA species in reticulocytes. Isolation of two P4.2 cDNAs implies existence of specific regulation of P4.2 expression in human RBCs. Human RBC P4.2 has significant homology with human factor XIII subunit a and guinea pig liver transglutaminase. Sequence alignment of P4.2 with these two transglutaminases, however, revealed that P4.2 lacks the critical cysteine residue required for the enzymatic crosslinking of substrates.

| S-EPMC53388 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data