Species variability in the modification of erythrocyte surface proteins by enzymatic probes.
Abstract: Bovine and equine erythrocytes have been studied by three different surface modification techniques to investigate the accessibility of the surface components to the external medium. Lactoperoxidase labeling of equine erythrocytes results in a significant labeling of only one membrane component, a 100 000-mol.wt polypeptide corresponding to the membrane-spanning Component III of human erythrocytes. The major sialoglycoprotein of the equine erythrocyte is not labeled. This is in contradistinction to the situation for human and bovine cells, where both components are labeled. The equine membrane sialoglycoprotein is also not markedly affected by pronase, chymotrypsin or trypsin treatment of whole cells under the treatment conditions used, although it can be cleaved by pronase in isolated membranes. Experiments with the isolated glycoprotein show that its cleavage by trypsin is quite selective, whereas cleavage by pronase and chymotrypsin is much more extensive. Labelling of bovine red cells by galactose oxidase treatment followed by reduction with 3H-labeled borohydride yields radioactivity in only one major peak, that corresponding increase in labeling. Equine erythrocytes don not show significant labeling by this technique unless a neuraminidase pretreatment has been performed. Then only the major glycoprotein is labeled. Thus the equine glycoprotein is apparently inaccessible to the cell surface by standard surface modification methods, although it is clearly a surface component. These experiments point out some of the limitations of surface labeling and proteolysis methods in probing the accessibility of membrane components. The results suggest that apparent inaccessibility of the equine glycoprotein is due partially to its structure and partially to its localization in the membrane.
Publication Date: 1975-03-13 PubMed ID: 1120155DOI: 10.1016/0005-2736(75)90176-5Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research article discusses a comparison of how proteins on the surface of horse and cattle red blood cells react to different modification techniques. It suggests that the way the proteins are structured and where they are located on the cell membrane makes them more or less accessible for modification.
Background and Objectives
- The study investigates the accessibility of surface proteins on bovine and equine erythrocytes (red blood cells) to the outside environment using three different surface modification techniques.
- The focus is on the modification of a 100 000-molecular weight polypeptide, also known as Component III, and a sialoglycoprotein, both of which are key components of the erythrocyte membrane.
Methods and Techniques
- The researchers used lactoperoxidase labeling, which resulted in the significant labeling of Component III in horse red blood cells, but not the sialoglycoprotein. This result differs from human and bovine cells, where both proteins are labeled.
- The scientists also utilized protease enzymes (pronase, chymotrypsin, trypsin) to study their effects on the sialoglycoprotein in whole cells and isolated membranes.
- Another technique used was labeling bovine red cells with galactose oxidase followed by reduction with tritium-labeled borohydride.
- A neuraminidase pretreatment was also conducted before labeling equine red cells using the technique mentioned above; this lead to the labeling of only the main glycoprotein.
Findings and Conclusion
- These techniques revealed that the equine membrane sialoglycoprotein was mostly unaffected by these treatments despite it being a surface component. This indicates its inaccessibility to these surface modification methods.
- The study suggests that the apparent inaccessibility is due to the structural makeup of the equine glycoprotein and its specific location in the membrane.
- The results underscore the limitations of surface labeling and proteolysis methods in probing the accessibility of membrane components, an important consideration when studying cell surface proteins and their functions.
Cite This Article
APA
Carraway KL, Colton DG, Shin BC, Triplett RB.
(1975).
Species variability in the modification of erythrocyte surface proteins by enzymatic probes.
Biochim Biophys Acta, 382(2), 181-192.
https://doi.org/10.1016/0005-2736(75)90176-5 Publication
Researcher Affiliations
MeSH Terms
- Alcohol Oxidoreductases
- Animals
- Cattle
- Cell Membrane / enzymology
- Erythrocytes / enzymology
- Galactose
- Glycoproteins / blood
- Horses
- Lactose
- Neuraminidase / metabolism
- Peroxidases
- Pronase / metabolism
- Species Specificity
- Trypsin / metabolism
Citations
This article has been cited 2 times.- Bell WC, Levy GN, Williams R, Aminoff D. Effect of galactose oxidase, with and without prior sialidase treatment, on the viability of erythrocytes in circulation. Proc Natl Acad Sci U S A 1977 Oct;74(10):4205-9.
- Howard RJ, Smith PM, Mitchell GF. Identification of differences between the surface proteins and glycoproteins of normal mouse (Balb/c) and human erythrocytes. J Membr Biol 1979 Aug;49(2):171-98.
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