Comparison of the binding of 59Fe- and 239Pu-transferrin to rat liver cell membranes

The binding of the 59Fe and 239Pu complexes of transferrin and 125I labelled transferrin [Tf (125I) ] to isolated cell membranes of rat liver has been studied. Transferrin forms a complex with an integral protein of the membrane which has an apparent molecular weight of about 180 kDa and is stable only at pH 7.4. Iron-59 is eluted from Sephacryl S 300 columns together with Tf (125I) or the Tf-membrane protein complex while 239Pu seems to be bound to different membrane protein(s). After isolation of the Tf-binding protein from 35S-labelled membranes and incubation with one of the metal-Tf complexes 59Fe elutes from a Sephacryl S 300 column together with 35S at an apparent molecular weight of ca. 250 kDa while 239Pu is found in fractions of lower molecular weight. It is concluded from these results that there are Tf-receptors in the liver cell membrane to which iron transferrin may bind. Plutonium, however, seems to be dissociated from Tf and bound directly to other membrane proteins.

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Isolation and partial characterization of a high molecular weight red cell membrane protein complex normally removed by the spleen

Blood ◽

10.1182/blood.v50.4.625.625 ◽

1977 ◽

Vol 50 (4) ◽

pp. 625-641 ◽

Cited By ~ 19

Author(s):

SE Lux ◽

KM John

Keyword(s):

Molecular Weight ◽

Cell Membrane ◽

Membrane Protein ◽

High Molecular Weight ◽

Protein Complex ◽

Red Cell ◽

Red Cell Membrane ◽

Membrane Protein Complex ◽

Cell Membrane Protein

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Isolation and partial characterization of a high molecular weight red cell membrane protein complex normally removed by the spleen

Blood ◽

10.1182/blood.v50.4.625.bloodjournal504625 ◽

1977 ◽

Vol 50 (4) ◽

pp. 625-641

Author(s):

SE Lux ◽

KM John

Keyword(s):

Molecular Weight ◽

Cell Membrane ◽

Membrane Protein ◽

High Molecular Weight ◽

Protein Complex ◽

Red Cell ◽

Red Cell Membrane ◽

Membrane Protein Complex ◽

Cell Membrane Protein

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Pathogenesis of shigella diarrhea. VII. Evidence for a cell membrane toxin receptor involving β1 {arrow} 4-linked N-acetyl-D-glucosamine oligomers

Journal of Experimental Medicine ◽

10.1084/jem.146.2.535 ◽

1977 ◽

Vol 146 (2) ◽

pp. 535-546 ◽

Cited By ~ 42

Author(s):

GT Keusch ◽

M Jacewicz

Keyword(s):

Cell Membrane ◽

Cholera Toxin ◽

Liver Cell ◽

Hela Cells ◽

Mammalian Cells ◽

Cell Membranes ◽

Proteolytic Enzymes ◽

Cell Monolayer ◽

Toxin Receptor ◽

Toxin Uptake

The binding of ShigeUa dysenteriae 1 cytotoxin to HeLa cells in culture and to isolated rat liver cell membranes was studied by means of an indirect consumption assay of toxicity from the medium, or by determination of cytotoxicity to the HeLa cell monolayer. Both liver cell membranes and HeLa cells removed toxicity from the medium during incubation, in contrast to WI-38 and Y-1 mouse adrenal tumor cells, both of which neither bound nor were affected by the toxin. Uptake of toxin was directly related to concentration of membranes added, time,and temperature, and indirectly related to the ionic strength of the buffer used. The chemical nature of the membrane receptor was characterized by using three principal approaches: (a) enzymatic sensitivity; (b) competitive inhibition and (c) receptor blockade studies. The receptor was destroyed by proteolytic enzymes, phospholipases (which markedly altered the gross appearance of the membrane preparation) and by lysozyme, but not by a variety of other enzymes. Of 28 carbohydrate and glycoprotein haptens studied, including cholera toxin and ganglioside, only the chitin oligosaccharide lysozyme substrates, per N-acetylated chitotriose, chitotetraose, and chitopentaose were effective competitive inhibitors. Greatest inhibition was found with the trimer, N, N', N" triacetyl chitotriose. Of three lectins studied as possible receptor blockers, including phytohemagglutinin, concanavalin A, and wheat germ agglutinin, only the latter, which is known to possess specific binding affinity for N, N', N" triacetyl chitotriose, was able to block toxin uptake. Evidence from all three approaches indicate, therefore, existence of a glycoprotein toxin receptor on mammalian cells, with involvement of oligomeric β1{arrow}4-1inked N-acetyl glucosamine in the receptor. This receptor is clearly distinct from the G(M1) ganglioside thought to be involved in the binding of cholera toxin to the cell membrane of a variety of cell types susceptible to its action.

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An integral membrane protein antigen associated with the membrane attachment sites of actin microfilaments is identified as an integrin beta-chain

Molecular and Cellular Biology ◽

10.1128/mcb.8.2.564-570.1988 ◽

1988 ◽

Vol 8 (2) ◽

pp. 564-570

Author(s):

P A Maher ◽

S J Singer

Keyword(s):

Molecular Weight ◽

Membrane Protein ◽

Protein Complex ◽

Apparent Molecular Weight ◽

Integral Membrane Protein ◽

Beta Chain ◽

Attachment Sites ◽

Wide Range ◽

Membrane Attachment

A monoclonal antibody (MAb 30B6) was recently described by Rogalski and Singer (J. Cell Biol. 101:785-801, 1985) which identified an integral membrane glycoprotein of chicken cells that was associated with a wide variety of sites of actin microfilament attachments to membranes. In this report, we present a further characterization of this integral protein. An immunochemical comparison was made of MAb 30B6 binding properties with those of two other MAbs, JG9 and JG22, which identify a component of a membrane protein complex that interacts with extracellular matrix proteins including fibronectin. We showed that the 110-kilodalton protein recognized by MAb 30B6 in extracts of chicken gizzard smooth muscle is identical, or closely related, to the protein that reacts with MAbs JG9 and JG22. These 110-kilodalton proteins are also structurally closely similar, if not identical, to one another as demonstrated by 125I-tryptic peptide maps. However, competition experiments showed that MAb 30B6 recognizes a different epitope from those recognized by MAbs JG9 and JG22. In addition, the 30B6 antigen is part of a complex that can be isolated on fibronectin columns. These results together establish that the 30B6 antigen is the same as, or closely similar to, the beta-chain of the protein complex named integrin, which is the complex on chicken fibroblast membranes that binds fibronectin. Although the 30B6 antigen is present in a wide range of tissues, its apparent molecular weight on gels varies in different tissues. These differences in apparent molecular weight are due, in large part, to differences in glycosylation.

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