The Journal of Cell Biology, Vol 71, 218-231, Copyright © 1976 by The Rockefeller University Press

ARTICLES

Variations in distribution of con A receptor sites and anionic groups during red blood cell differentiation in the rat

E Skutelsky and MG Farquhar

The distribution of receptors for concanavalin A (Con A) and anionic groups on plasma membranes of developing blood cells was investigated in the rat. Glutaraldehyde-fixed bone marrow and circulating blood cells were exposed to ferritin-conjugated Con A or positively chaged ferric oxide (CI) and processed for electro n microscopy. The frequency of Con A and CI binding sites varied during different erythroid developmental stages and amont different leukoid cell types. There was a constant inverse relationship between Con A and CI binding sites. Among leukoid cells, Con A binding was high on plasma cells and macrophages, lower on neutrophils and lymphocytes, and still lower on eosinophils and basophils; CI binding was highest in the latter and lowest in plasma cells and macrophages. Among erythroid cells, there was a progressive increase in Con A and a decrease in CI binding after successive divisions of erythroblasts, and a progressive decrease in Con A and an increase in CI binding upon maturation of the orthochromatic erythroblast to the reticulocyte. The most pronounced modification in distribution of these sites occurred during nuclear expulsion: that protion of the plasma membrane surrounding the extruded nucleus was heavily labeled by Con A (up to four times that of the orthochromatic erythroblast) whereas the reticulocyte had considerably fewer sites. The situation was reversed with CI. The results suggest that the concentration of nonsialated glycoproteins (to which Con A binds) varies inversely to that of sialoproteins (to which CI binds) in the membrane of the differentiating erythroid cell. The remarkable changes observed at the time of nuclear extrusion suggest that there is either local modification of glycosylated groups with removal of sialyl residues from the membrane surrounding the extruded nucleus of selective segregation of membrane glycoproteins leading to a high concentration of sialoproteins (glycophroin) in the membrane of the mature erythrocyte.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

• Lee, J. C.-M., Gimm, J. A., Lo, A. J., Koury, M. J., Krauss, S. W., Mohandas, N., Chasis, J. A. (2004). Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity. Blood 103: 1912-1919 [Abstract] [Full Text]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents