scholarly journals LYMPHOCYTE MEMBRANE DYNAMICS

1971 ◽  
Vol 134 (6) ◽  
pp. 1373-1384 ◽  
Author(s):  
Robert E. Cone ◽  
John J. Marchalonis ◽  
Ronald T. Rolley

Cell surface proteins of normal and neoplastic lymphocytes were labeled with iodide-125I by lactoperoxidase-catalyzed iodination. Incubation of 125I-labeled iodide cells in vitro resulted in the release of iodinated surface proteins at a rapid rate which was dependent on cellular respiration and protein synthesis. Comparisons by disc electrophoresis showed a marked similarity between urea-soluble surface proteins extracted from iodinated cells and iodinated material released by the cells during in vitro incubation. The rate of release of cell surface proteins from thymus cells was three times faster than that of spleen cells or bone marrow-derived thoracic duct lymphocytes. In addition, different proteins were released at different rates as evidenced by the rate of release of 125I of rabbit anti-mouse immunoglobulin specifically bound to mouse spleen cells and comparisons by disc electrophoresis of urea-soluble iodinated surface proteins extracted from cells before and after incubation. The results suggest that a dynamic state exists at the cell surface. The possible role of the release of cell surface proteins in cell regulation and communication is discussed.

2021 ◽  
Vol 7 (4) ◽  
pp. 262
Author(s):  
Anuja Paudyal ◽  
Govindsamy Vediyappan

Candida auris is an emerging antifungal resistant human fungal pathogen increasingly reported in healthcare facilities. It persists in hospital environments, and on skin surfaces, and can form biofilms readily. Here, we investigated the cell surface proteins from C. auris biofilms grown in a synthetic sweat medium mimicking human skin conditions. Cell surface proteins from both biofilm and planktonic control cells were extracted with a buffer containing β-mercaptoethanol and resolved by 2-D gel electrophoresis. Some of the differentially expressed proteins were excised and identified by mass spectrometry. C. albicans orthologs Spe3p, Tdh3p, Sod2p, Ywp1p, and Mdh1p were overexpressed in biofilm cells when compared to the planktonic cells of C. auris. Interestingly, several proteins with zinc ion binding activity were detected. Nrg1p is a zinc-binding transcription factor that negatively regulates hyphal growth in C. albicans. C. auris does not produce true hypha under standard in vitro growth conditions, and the role of Nrg1p in C. auris is currently unknown. Western blot analyses of cell surface and cytosolic proteins of C. auris against anti-CalNrg1 antibody revealed the Nrg1p in both locations. Cell surface localization of Nrg1p in C. auris, an unexpected finding, was further confirmed by immunofluorescence microscopy. Nrg1p expression is uniform across all four clades of C. auris and is dependent on growth conditions. Taken together, the data indicate that C. auris produces several unique proteins during its biofilm growth, which may assist in the skin-colonizing lifestyle of the fungus during its pathogenesis.


1997 ◽  
Vol 272 (3) ◽  
pp. L494-L503
Author(s):  
L. Chen ◽  
V. Shick ◽  
M. L. Matter ◽  
S. M. Laurie ◽  
R. C. Ogle ◽  
...  

Cell adhesion to amino acids 2179-2198 (SN-peptide) of the laminin-1 alpha1-chain is required for lung alveolar formation in vitro (M. L. Matter and G. W. Laurie. J. Cell Biol. 124: 1083-1090, 1994). The nature of the SN-peptide receptor(s) was probed with neutralizing anti-integrin monoclonal antibodies (MAb), cells lacking integrin subunits, soluble heparin, and SN-peptide columns. Cell adhesion and spreading studies confirmed the specificity of SN-peptide and revealed adhesion to be unaffected by inclusion of anti-beta1-, anti-alpha(2-6)- or anti-alpha(V)beta5-integrin MAb. Cells lacking beta1- or alpha6-integrin subunits were fully adherent. Adhesion was heparin, but not chondroitin sulfate or heparinase, sensitive, much as is alpha-dystroglycan-laminin-1 binding. Heparin eluted approximately 155- and 180-kDa cell-surface proteins from SN-peptide columns. An additional approximately 91-kDa protein was eluted by EDTA. All were unrecognized by anti-beta1-integrin MAb. SN-peptide therefore interacts with three cell-surface proteins for which the identity remains to be determined.


1983 ◽  
Vol 96 (4) ◽  
pp. 1040-1046 ◽  
Author(s):  
WJ Brown ◽  
WA Shannon ◽  
WJ Snell

The compositional relationship between the cell surface of rabbit polymorphonuclear leukocytes (PMNs) and the membranes of PMN cytoplasmic granules has been investigated. Heterophilic PMNs obtained from peritoneal exudates contained 13 cell surface polypeptides ranging in molecular weight from 220,000 to 12,000 daltons as determined by lactoperoxidase-catalyzed protein iodination and gel electrophoresis. Of these, four polypeptides co-migrated with proteins identified as the major constituents of specific (SpG) and azurophilic (AzG) granule membranes. The most notable of these were cell surface proteins of 145,000 and 96,000 daltons that co-migrated with proteins identified as granule content proteins released from PMNs during exocytosis. Extensive washing did not remove these proteins from the cell surface. Iodination of PMNs after the release of SpG and AzG contents by calcium ionophore- induced exocytosis revealed that there was not a dramatic quantitative change in the proteins on the cell surface. Instead, there were large, quantitative increases in the relative amounts of (125)I that were incorporated into several pre-existing cell surface proteins; all of these cell surface proteins co-migrated as a set with those polypeptides identified as either granule membrane or content proteins. Although nearly all of the major polypeptides of SpG and AzG had counterparts on the cell surface of freshly isolated peritoneal exudates PMNs, there were several polypeptides that were unique to the cell surface. Thus, the PMN has at least three membrane compartments with strikingly different protein compositions.


1978 ◽  
Vol 312 (1 Fibroblast Su) ◽  
pp. 406-409 ◽  
Author(s):  
J. R. Hassell ◽  
J. P. Pennypacker ◽  
K. M. Yamada ◽  
R. M. Pratt

1981 ◽  
Vol 88 (3) ◽  
pp. 591-598 ◽  
Author(s):  
JM Kuby ◽  
L Wofsy

An experimental system was developed in which the majority of all lymphocyte cell-surface proteins, regardless of antigenic specificity, could be cross-linked and redistributed in the membrane to determine whether this would induce a corresponding redistribution of intramembrane particles (IMP). Mouse spleen cells were treated with P-diazoniumphenyl- β-D-lactoside (lac) to modify all exposed cell-surface proteins. Extensive azo- coupling was achieved without significantly reducing cell viability or compromising cellular function in mitogen- or antigen-stimulated cultures. When the lac-modified cell- surface proteins were capped with a sandwich of rabbit antilactoside antibody and fluorescein-goat anti-rabbit Ig, freeze-fracture preparations obtained from these cells revealed no obvious redistribution of IMP on the majority of fracture faces. However, detailed analysis showed a statistically significant 35 percent decrease (P less than 0.01) in average IMP density in the E face of the lac-capped spleen cells compared with control cells, whereas a few E-face micrographs showed intense IMP aggregation. In contrast, there was no significant alteration of P-face IMP densities or distribution. Apparently, the majority of E-face IMP and virtually all P-face IMP densities or distribution. Apparently, the majority of E-face IMP and virtually all P-face IMP do not present accessible antigenic sites on the lymphocyte surface and do not associate in a stable manner with surface protein antigens. This finding suggests that IMP, as observed in freeze-fracture analysis, may not comprise a representative reflection of lymphocyte transmembrane protein molecules and complexes because other evidence establishes: (a) that at least some common lymphocyte surface antigens are indeed exposed portions of transmembrane proteins and (b) that the aggregation of molecules of any surface antigen results in altered organization of contractile proteins at the cytoplasmic face of the membrane.


2021 ◽  
Author(s):  
Takeshi Imai ◽  
Ryuta Tobe ◽  
Koji Honda ◽  
Mai Tanaka ◽  
Jun Kawamoto ◽  
...  

Oxidative stress–mediated formation of protein hydroperoxides can induce irreversible fragmentation of the peptide backbone and accumulation of cross-linked protein aggregates, leading to cellular toxicity, dysfunction, and death. However, how bacteria protect themselves from damages caused by protein hydroperoxidisation is unknown. Here we show that YjbI, a group II truncated haemoglobin from Bacillus subtilis, prevents oxidative aggregation of cell-surface proteins by its biologically unprecedented protein hydroperoxide peroxidase-like activity, which removes hydroperoxide groups from oxidised proteins. Disruption of the yjbI gene in B. subtilis lowered biofilm water repellence and the mechanical stiffness of the cell surface, which associated with the cross-linked aggregation of the biofilm matrix protein TasA. YjbI was localised to the cell surface, and the sensitivity of planktonically grown cells to generators of reactive oxygen species was significantly increased upon yjbI disruption, suggesting that YjbI pleiotropically protects labile cell-surface proteins from oxidative damage. YjbI removed hydroperoxide residues from a model oxidised protein substrate, bovine serum albumin, and prevented its oxidative aggregation in vitro. These findings provide new insights into the role of truncated haemoglobin and the importance of hydroperoxide removal from proteins in the survival of aerobic bacteria.


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