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PubMed1983

An approach to the cloning of cell surface protein genes. Selection by cell sorting of mouse L-cells that express HLA or 4F2 antigens after transformation with total human DNA.

We describe an approach to the cloning of cell surface proteins that is independent of messenger RNA isolation. Mouse Ltk- cells are cotransformed with the thymidine kinase gene from Herpes Simplex Virus and total human DNA. Transformants expressing the human surface antigens of interest are isolated by two selection steps, consisting of treatment with hypoxanthine/aminopterin/thymidine and fluorescence-activated cell sorting. Using this procedure, we isolated seven transformants expressing HLA-A,B,C antigens and 12 transformants expressing the 4F2 antigen. We have so far failed to identify any OKT-10 antigen expressing L-cell transformants. Three independent secondary 4F2 transformants were obtained after identical cotransformation of fresh Ltk- cells with DNA from primary transformants. Analysis of their genome by hybridization with human DNA revealed a shared set of human restriction fragments in all three cell lines. This 32 X 10(3) base-pair segment of DNA codes for the human 4F2 antigen, thereby offering the opportunity to clone the gene. To substantiate this hypothesis, we analyzed the seven HLA-expressing cell lines, and we found that all of them had acquired an HLA-coding sequence concomitant to its expression.

Animals↗
PubMed1978

Transformation-sensitive cell surface protein: isolation, characterization, and role in cellular morphology and adhesion.

Cell surface protein is the major cell surface glycoprotein of chick embryo fibroblasts. We have isolated and purified this glycoprotein and find that it is an adhesive protein that increases cell-cell and cell-substratum adhesiveness in a variety cellular adhesion assays. Transformation of chick fibroblasts results in decreased quantities of CSP due primarily to a fivefold reduction in CSP biosynthesis, although increased proteolytic degradation and shedding from the cell surface also contribute. The decreased biosynthesis is apparently due to a fivefold reduction in translatable mRNA for CSP. Reconstitution of isolated purified CSP on 14 transformed cell lines from several species results in reversion to a more normal fibroblastic morphology, adhesiveness, cell surface architecture, microfilament bundle organization, motility, and alignment at confluence. Cell surface protein does not restore growth control. The effects of CSP appear to be due to at least two actions, increased cell-substratum adhesion plus altered cell-cell interactions. Untransformed chick cells treated with affinity-purified antibodies to CSP develop the rounded morphology characteristic of many transformed cells that are deficient in CSP (LETS protein). Cell surface protein is found primarily in fibrillar aggregates on the cell surface. These CSP fibrils are relatively immobile and do not affect the mobility of other cell surface components. However, CSP can be eventually redistributed to caplike structures with anti-CSP. Isolated CSP consists of highly asymmetric disulfide-linked dimers and multimers. The interchain disulfide bridges are confined to a short terminal fragment that is readily removed by trypsin. Cell surface protein and cold-insoluble globulin have similar compositions but differ in solubility and amino termini. Cell surface protein contains primarily asparagine-linked oligosaccharides that appear to be responsible for CSP's concanavalin A receptor activity. Inhibition of CSP's glycosylation by treatment with tunicamycin results in decreased CSP due to marked increases in its degradation rate, without inhibition of synthesis or secretion. Studies of this major cell surface glycoprotein have provided insight into the biochemical mechanisms of cellular adhesion, morphology, and social interaction and provide an approach to analyze the dynamics and regulation of protein synthesis, glycosylation, secretion, and turnover.

Animals↗
PubMed1989

Novel phase-shift marker in cell surface proteins of Bordetella bronchiseptica.

Cell surface proteins of phase I cultures of Bordetella bronchiseptica strains from various species of animals were compared with those of isogenic phase III cultures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A protein band with a molecular mass of 74 kilodaltons was found only in various phase I cultures. This protein disappeared in parallel with antigenic modulation and had strong antigenicity. We found it to be an appropriate phase-shift marker for two reasons: it was readily extracted and recognized, and it was specifically identified by its distinct antigenicity.

Animals↗
PubMed2005

Combined affinity labelling and mass spectrometry analysis of differential cell surface protein expression in normal and prostate cancer cells.

Differences in the expression of cell surface proteins between a normal prostate epithelial (1542-NP2TX) and a prostate cancer cell line (1542-CP3TX) derived from the same patient were investigated. A combination of affinity chromatographic purification of biotin-tagged surface proteins with mass spectrometry analysis identified 26 integral membrane proteins and 14 peripheral surface proteins. The findings confirm earlier reports of altered expression in prostate cancer for several cell surface proteins, including ALCAM/CD166, the Ephrin type A receptor, EGFR and the prostaglandin F2 receptor regulatory protein. In addition, several novel findings of differential expression were made, including the voltage-dependent anion selective channel proteins Porin 1 and 2, ecto-5'-nucleotidase (CD73) and Scavenger receptor B1. Cell surface protein expression changed both qualitatively and quantitatively when the cells were grown in the presence of either or both interferon INFalpha and INFgamma. Costimulation with type I and II interferons had additive or synergistic effects on the membrane density of several, mainly peripherally attached surface proteins. Concerted upregulation of surface exposed antigens may be of benefit in immuno-adjuvant-based treatment of interferon-responsive prostate cancer. In conclusion, this study demonstrates that differences in the expression of membrane proteins between normal and prostate cancer cells are reproducibly detectable following vectorial labelling with biotin, and that detailed analysis of extracellular-induced surface changes can be achieved by combining surface-specific labelling with high-resolution two-dimensional gel electrophoresis and mass spectrometry.

Cell Line, Tumor↗
PubMed1998

A novel Dictyostelium cell surface protein important for both cell adhesion and cell sorting.

A mutant of Dictyostelium that is aberrant in the process of tip formation (dtfA-: defective in tip formation A) has been isolated by gene tagging. The dtfA gene is predicted to encode a protein of 163 kDa. There are no extensive sequence homologies between DTFA and previously identified proteins, but four short N-terminal sequence motifs show partial homology to repeats found in mammalian mucins. Immunofluorescence reveals a lattice-like arrangement of DTFA protein at the cell surface. When developing on a bacterial lawn, cells of the mutant strain (dtfA- cells) aggregate to form tight mounds, but development then becomes arrested. When developed in the absence of nutrients, a fraction of dtfA- cells complete development, but there is a long delay at the tight mound stage and the culminants that eventually form are aberrant. In such dtfA- mounds the prestalk cells fail to move to the apex on cue and so tip formation is delayed. dtfA- cells also show a conditional defect in early development, in that they are unable to aggregate when plated at low density. In addition dtfA- cells do not agglomerate efficiently when shaken in suspension. In combination, these results suggest that DTFA may form part of a cell-cell adhesion system that is needed both for optimal aggregation and for efficient cell sorting during multicellular development. The DTFA protein also appears to be important during cell growth, because cytokinesis is defective and the actin cytoskeleton aberrant in growing dtfA- cells.

Amino Acid Sequence↗
PubMed2004

In silico evaluation of two mass spectrometry-based approaches for the identification of novel human leukocyte cell-surface proteins.

The identification and quantitation of cell-surface proteins expressed by leukocytes currently use the wide availability of monoclonal antibodies (mAb) in immunohistochemical and flow cytometric assays. Presently, approximately 400 such proteins have been characterized; however, analysis of the completed human genome sequence indicates that it may contain several thousand as-yet unidentified molecules, which may be expressed on the leukocyte cell surface. Recent advances in protein isolation and analysis using mass spectrometry illustrate that it is now feasible to identify the protein composition of a complex sample such as a plasma membrane extract. Such an approach may be useful for the identification of the cell-surface proteins that have not been identified using mAb techniques. Here, we detail the results of an in silico evaluation of the peptides isolated using two methods used to label plasma membrane proteins to determine whether these methods are suitable for the identification of known leukocyte cell-surface proteins by mass spectrometry. The labeling of cell-surface proteins before isolation and characterization is a valuable means of differentiating between plasma membrane and internal membrane proteins The results indicate that although the majority of cell-surface proteins can be identified using either of the approaches, others known to be important diagnostically and/or therapeutically would not be identified using either approach. The implication of this for the use of these techniques in the discovery of new leukocyte cell-surface proteins is discussed.

Amino Acid Sequence↗
PubMed1993

Distribution of gp138, a cell surface protein responsible for sexual cell fusion, among cellular slime moulds.

Sexual cell fusion occurs between NC4 and HM1, heterothallic strains of Dictyostelium discoideum. Several cell surface proteins relevant to the process have been identified. One of them, gp138, exists in fusion-competent cells of both NC4 and HM1, and is considered to be more concerned with membrane fusion than gamete recognition. In this study, we raised monoclonal antibodies against gp138 and examined gp138 distribution among strains and species of cellular slime moulds to confirm its importance in sexual cell fusion. All heterothallic and bisexual D. discoideum strains examined were found to possess gp138, while asexual and homothallic strains lacked it. The anti-gp138 monoclonal antibody detected several distinct proteins in homothallic strains and one in an asexual strain. Some of the former proteins appeared together with the increase in binucleated cells. Cells of Dictyostelium mucoroides and Polysphondylium pallidum did not possess proteins reactive to the monoclonal antibody. These results indicate that gp138 is common among, but restricted to, cross-matable strains of D. discoideum. Our results also support previously published molecular phylogenetic studies which suggest that homothallic and asexual strains of D. discoideum are remote from other strains of D. discoideum but are less distantly related to them than other species are.

Animals↗
PubMed1996

HKR1 encodes a cell surface protein that regulates both cell wall beta-glucan synthesis and budding pattern in the yeast Saccharomyces cerevisiae.

We previously isolated the Saccharomyces cerevisiae HKR1 gene that confers on S. cerevisiae cells resistance to HM-1 killer toxin secreted by Hansenula mrakii (S. Kasahara, H. Yamada, T. Mio, Y. Shiratori, C. Miyamoto, T. Yabe, T. Nakajima, E. Ichishima, and Y. Furuichi, J. Bacteriol. 176:1488-1499, 1994). HKR1 encodes a type 1 membrane protein that contains a calcium-binding consensus sequence (EF hand motif) in the cytoplasmic domain. Although the null mutation of HKR1 is lethal, disruption of the 3' part of the coding region, which would result in deletion of the cytoplasmic domain of Hkr1p, did not affect the viability of yeast cells. This partial disruption of HKR1 significantly reduced beta-1,3-glucan synthase activity and the amount of beta-1,3-glucan in the cell wall and altered the axial budding pattern of haploid cells. Neither chitin synthase activity nor chitin content was significantly affected in the cells harboring the partially disrupted HKR1 allele. Immunofluorescence microscopy with an antibody raised against Hkr1p expressed in Escherichia coli revealed that Hkr1p was predominantly localized on the cell surface. The cell surface localization of Hkr1p required the N-terminal signal sequence because the C-terminal half of Hkr1p was detected uniformly in the cells. These results demonstrate that HKR1 encodes a cell surface protein that regulates both cell wall beta-glucan synthesis and budding pattern and suggest that bud site assembly is somehow related to beta-glucan synthesis in S. cerevisiae.

Bacterial Outer Membrane Proteins↗
PubMed1983

Changes in pattern and accessibility for 125I-labelling of cell-surface proteins after mesenchymal differentiation of embryonal carcinoma cells.

Cell-surface proteins of the embryonal carcinoma line C17-S1 1003 (1003) and of some of its mesenchymal derivatives were studied. The surface proteins were labelled with 125I using the lactoperoxidase-glucose-glucose oxidase system either on the cells attached to the culture dishes or after their dissociation. Iodinated proteins were analyzed by two-dimensional gel electrophoresis. The patterns obtained with embryonal carcinoma cells 1003 and with two mesenchymal cell types derived from them, namely embryonic mesenchymal cells (line 10035) and fibroblastic cells (line 10031), were different one from the other, especially when considering the group of proteins labelled on the attached cells. The pattern of cell-surface proteins of the myoblastic line 1168, also derived from C17-S1, was found to be similar to that of 10031 fibroblastic cells. This result is discussed in the light of the phenotypic transition toward myogenesis, which can be obtained with 10031 fibroblastic cells but not with 10035 embryonic mesenchymal cells. A direct method of detection of lectin-binding proteins permitted us to identify the major concanavalin A-binding proteins. Two of them are common to all cell lines studied. They were labeled with 125I on the attached undifferentiated 1003 cells, while in all differentiated derivatives they became available for labelling after the cell detachment only.

Animals↗
PubMed1976

Differences in cell surface proteins of drug resistant and sensitive cell lines.

Lactoperoxidase catalyzed iodination of cell surface proteins has been used to compare theophylline and ouabain resistant variants with the drug sensitive parental cell lines. In cells showing contact inhibition a high molecular weight protein was observed to be preferentially labelled. In contrast this was not observed for non contact inhibited cells. These results support a previously suggested correlation between growth regulation and the exposure of this cell surface protein.

Animals↗
PubMed2004

Specific labeling of cell surface proteins with chemically diverse compounds.

The specific and covalent labeling of fusion proteins with synthetic molecules opens up new ways to study protein function in the living cell. Here we present a novel method that allows for the specific and exclusive extracellular labeling of proteins on the surfaces of live cells with a large variety of synthetic molecules including fluorophores, protein ligands, or quantum dots. The approach is based on the specific labeling of fusion proteins of acyl carrier protein with synthetic molecules through post-translational modification catalyzed by phosphopantetheine transferase. The specificity and versatility of the labeling should allow it to become an important tool for studying and manipulating cell surface proteins and for complementing existing approaches in cell surface engineering.

Acyl Carrier Protein↗
PubMed1994

Salmonella typhimurium induces selective aggregation and internalization of host cell surface proteins during invasion of epithelial cells.

Salmonella interact with eucaryotic membranes to trigger internalization into non-phagocytic cells. In this study we examined the distribution of host plasma membrane proteins during S. typhimurium invasion of epithelial cells. Entry of S. typhimurium into HeLa epithelial cells produced extensive aggregation of cell surface class I MHC heavy chain, beta 2-microglobulin, fibronectin-receptor (alpha 5 beta 1 integrin), and hyaluronate receptor (CD-44). Other cell surface proteins such as transferrin-receptor or Thy-1 were aggregated by S. typhimurium to a much lesser extent. Capping of these plasma membrane proteins was observed in membrane ruffles localized to invading S. typhimurium and in the area surrounding these structures. In contrast, membrane ruffling induced by epidermal growth factor only produced minor aggregations of surface proteins, localized exclusively in the membrane ruffle. This result suggests that extensive redistribution of these proteins requires a signal related to bacterial invasion. This bacteria-induced process was associated with rearrangement of polymerized actin but not microtubules, since preincubation of epithelial cells with cytochalasin D blocked aggregation of these proteins while nocodazole treatment did not. Of the host surface proteins aggregated by S. typhimurium, only class I MHC heavy chain was predominantly present in the bacteria-containing vacuoles. No extensive aggregation of host plasma membrane proteins was detected when HeLa epithelial cells were infected with invasive bacteria that do not induce membrane ruffling, including Yersinia enterocolitica, a bacterium that triggers internalization via binding to beta 1 integrin, and a S. typhimurium invasion mutant that utilizes the Yersinia-internalization route. In contrast to the situation with S. typhimurium, class I MHC heavy chain was not selectively internalized into vacuoles containing these other bacteria. Extensive aggregation of host plasma membrane proteins was also not observed when other S. typhimurium mutants that are defective for invasion were used. The amount of internalized host plasma membrane proteins in the bacteria-containing vacuoles decreased over time with all invasive bacteria examined, indicating that modification of the composition of these vacuoles occurs. Therefore, our data show that S. typhimurium induces selective aggregation and internalization of host plasma membrane proteins, processes associated with the specific invasion strategy used by this bacterium to enter into epithelial cells.

Adhesins, Bacterial↗
PubMed1987

Changes in the cell surface protein composition of human alveolar macrophages induced by smoking.

The cell surface proteins of human alveolar macrophages obtained from nonsmokers have been compared to those of alveolar macrophages obtained from smokers. Proteins of nonsmokers' alveolar macrophages surface labeled with 125I differed from those of smokers' alveolar macrophages, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Three major radiolabeled proteins with molecular weights of 183,000, 80,000, and 30,000 were identified in fresh smokers' cells. The major radiolabeled protein of nonsmokers' macrophages had an apparent molecular weight of approximately 183,000. Affinity chromatography suggested the Mr 183,000 protein is a mannose receptor. In contrast, the molecular weight of the major radiolabeled protein of smokers' alveolar macrophages was approximately 30,000; the Mr 183,000 protein was less prominent. When nonsmokers' alveolar macrophages were cultured in vitro before 125I labeling, the cell surface protein pattern changed to resemble that of smokers' alveolar macrophages; the Mr 183,000 protein could no longer be detected on the cell surface, whereas a Mr 80,000 protein was increased in quantity and a new Mr 30,000 protein was detected. Nonadherent macrophages showed similar changes in their surface-labeled proteins but also contained a new prominently labeled Mr 70,000 protein. Limited proteolysis peptide mapping with five different enzymes did not reveal any evidence of homology among the Mr 183,000, 80,000, 70,000, and 30,000 proteins. The differences in cell surface protein composition between alveolar macrophages of smokers and nonsmokers may reflect their functional capabilities or their state of "activation" and may be mechanistically important in the development of various pulmonary diseases seen in smokers including cancer. These results also demonstrate that major changes in the surface proteins of the human alveolar macrophage plasma membrane can occur rapidly following manipulation.

Affinity Labels↗
PubMed1996

Effects of systemic fluconazole therapy on in vitro adhesion of Candida albicans to buccal epithelial cells and changes of the cell surface proteins of the epithelial cells.

This paper presented the effects of systemic fluconazole therapy via intravenous (IV) and oral (PO) administrations on the adhesion of Candida albicans (C. albicans) to the buccal epithelial cells (BEC) from five treated patients with three candidosis, one mucormycosis and one sporotrichosis and at the same time, an analysis of the cell surface proteins involving candidal adherent receptor in the BEC of the patients in the course of 7 days were exposed to 3H-leucine radiolabeled C. albicans for in vitro candidal adherent assay, and the BEC from first intake day and the last intake day of the patients were extracted by dithiothreitol (DTT)-iodoacetamide treatment for SDS-PAGE. These results indicate that the systemic fluconazole therapy results in the inhibitory effect of candidal adhesion to BEC of treated patients to prevent them from oral candidosis for a prolonged time, which is based on the absent surface protein (35 KDa) of the BEC.

Adult↗
PubMed1983

The serological properties of the cell surface proteins of Vibrio cholerae.

The serological properties of cell surface proteins of Vibrio cholerae belonging to both the biotypes (classical and El Tor) and the serotypes (Ogawa and Inaba) were investigated. Proteins were isolated by extracting V. cholerae with EDTA in the presence of sodium chloride. The surface localization of these proteins was confirmed with (a) radioiodinated protein A as an immunoprobe and (b) antiserum absorption studies with whole bacteria. There were similarities among the polypeptides of cell surface proteins isolated from various V. cholerae types. Antisera to these proteins agglutinated several V. cholerae strains, irrespective of biotype, serotype and antibiotic sensitivity. The antisera did not agglutinate pathogenic enteric bacteria such as enterotoxigenic Escherichia coli, Salmonella typhi, Shigella spp., Aeromonas hydrophila and Yersinia enterocolitica. The cell surface proteins of V. cholerae were immunogenic in rabbits as high titres of anti-protein specific antibodies were detected by the ELISA technique in the immune sera. These results suggest that the cell surface proteins are common antigens of V. cholerae and can be developed as a potential vaccine candidate against cholera.

Agglutination Tests↗
PubMed1998

Identification of pactolus, an integrin beta subunit-like cell-surface protein preferentially expressed by cells of the bone marrow.

We have sought to develop methodologies to identify genes that are preferentially expressed during the differentiation of mast cells from their hematopoietic stem cell precursors. By using a modified differential display protocol, we compared a subset of transcripts expressed in bone marrow cells differentiated into immature mast cells with the exogenous addition of stem cell factor (SCF) or interleukin 3. One gene was identified that was preferentially expressed in the SCF-derived cells and encodes a novel murine integrin beta subunit-like molecule, dubbed Pactolus-1 (Pactolus). Two distinct forms of Pactolus mRNA were detected which, via alternative splicing, are predicted to encode a membrane-bound form and truncated version of the protein. The full-length Pactolus gene product is very similar to a number of beta subunit integrin chains, particularly beta2, with the notable exceptions of the apparent deletion of the metal-binding site within the putative metal ion-dependent adhesion site-like domain of the Pactolus gene product and a cytoplasmic domain that shares no obvious homology to similar domains of the other beta subunit integrin proteins. Although the Pactolus sequence was first identified in immature mast cell samples, screening of murine tissues indicated the highest level of Pactolus expression was found in the bone marrow, suggesting that the expression of Pactolus is confined to immature and maturing bone marrow-derived cells, and that the SCF-derived mast cells are more representative of this state than are the interleukin 3-derived mast cells. Immunoprecipitation of Pactolus revealed a cell-surface protein with an apparent molecular mass of about 95 kDa. Surprisingly, no associating alpha integrin subunit could be identified suggesting that either Pactolus does not associate with another integrin subunit or the association is too weak to be identified. These data suggest that Pactolus represents a gene and gene product related to those of the integrin beta subunits but whose function(s) may be quite distinct from those of the integrin beta subunits.

Alternative Splicing↗
PubMed1998

Binding of Escherichia coli verotoxins to cell surface protein on wild-type and globotriaosylceramide-deficient Vero cells.

We have examined verotoxin (VT) binding to cell surface proteins. When Vero or globotriaosylceramide (Gb3) deficient Vero (VRP) cells were incubated with 125I-labelled verotoxin 2(VT2) and disuccinimidyl suberate cross-linker, SDS-PAGE of cell lysates showed radiolabelled bands at 44, 50, 60, 86, 102, and 138 kDa. When 125I-labelled verotoxin 1 (VT1) was cross-linked, radioactive bands occurred at 51, 67, 101, 160, 188, and 232 kDa. In contrast, 125I-labelled VT1 B subunit produced a single radioactive band migrating at 50 kDa. CHO cells did not bind labelled VT. VT2 binding to VRP cells fit a rectangular hyperbola suggesting a single class of binding sites. In contrast, VT1 and VT1 B subunit binding to VRP cells was best fit by sigmoidal curves suggesting the presence of positive cooperativity between at least two binding sites. Scatchard analysis of VT2 binding data yielded 3.5 x 10(9) molecules bound/microgram of cell protein with an equilibrium dissociation constant (KD) of 13 nM. The apparent KD was 9.7nM for VT1 and 73.2 nM for VT1 B subunit. These results indicate that VT binds to a protein, or proteins, on the surface of susceptible cells and that there appear to be differences between VT1 and VT2 binding. Interactions between VT1 or VT2 and the proteins demonstrated here may be important in the biological activity of VT.

Animals↗
PubMed1983

Export of major cell surface proteins is blocked in yeast secretory mutants.

The transport of newly synthesized proteins to the yeast cell surface has been analyzed by a modification of the technique developed by Kaplan et al. (Kaplan, G., C. Unkeless, and Z.A. Cohn, 1979, Proc. Natl. Acad. Sci. USA, 76:3824-3828). Cells metabolically labeled with (35)SO(4)(2-) are treated with trinitrobenzenesulfonic acid (TNBS) at 0 degrees C under conditions where cell-surface proteins are tagged with trinitrophenol (TNP) but cytoplasmic proteins are not. After fractionation of cells into cell wall, membrane and cytoplasmic samples, and solubilization with SDS, the tagged proteins are immunoprecipitated with anti-TNP antibody and fixed staphylococcus aureus cells. Analysis of the precipitates by SDS gel electrophoresis and fluorography reveals four major protein species in the cell wall (S(1)-S(4)), seven species in the membrane fraction (M(1)-M(7)), and no tagged proteins in the cytoplasmic fraction. Temperature-sensitive mutants defective in secretion of invertase and acid phosphatase (sec mutants; Novick, P., C. Field, and R. Schekman, 1980, Cell, 21:204-215) are also defective in transport of the 11 major cell surface proteins at the nonpermissive temperature (37 degrees C). Export of accumulated proteins is restored in an energy- dependent fashion when secl cells are returned to a permissive temperature (24 degrees C). In wild-type cells the transit time for different surface proteins varies from less than 8 min to about 30 min. The asynchrony is developed at an early stage in the secretory pathway. All of the major cell wall proteins and many of the externally exposed plasma membrane proteins bind to concanavalin A. Inhibition of asparagine-linked glycosylation with tunicamycin does not prevent transport of several surface proteins.

Cell Membrane↗