Substrate heterogeneity of component a of the human erythrocyte membrane

Abstract

Component a of the erythrocyte membrane is a specific substrate for endogenous protein kinase activity and its phosphorylation is significantly decreased under assay conditions in myotonic muscular dystrophy (Roses, A.D., and Appel, S.H.J. Membr. Biol 20:51-58 (1975)). We have demonstrated substrate heterogeneity of two fractions of component a separated by concanavalin A (Con-A) sepharose chromatography. The fraction of component a that is retarded by Con A and eluted with alpha-methyl-D-glucoside does not accept the transfer of phosphate from [gamma-32 P] ATP as a substrate for endogenous protein kinase activity. The nonretarded fraction contains greater than 90% of the radioactive label. These experiments also confirm the carbohydrate heterogeneity of component a (Findley, J.B.C., J. Biol. Chem. 249:4398 (1974).

Stoichiometry of sodium and potassium transport in erythrocytes from patients with myotonic muscular dystrophy.

“…No differences could be demonstrated in the level of acyl phosphorylation in MyD erythrocytes (A. D. Roses, unpublished data), but a definite decrease was noted in the ester phosphorylation of serine and threonine in band III . Whether the specific component of band III, in which the difference in phosphoserine and phosphothreonine formation occurs, is also the Na+ K+ ATPase or some other constituent is still under investigation (Roses, 1975). This possible alteration of Na+ K+ ATPase phosphorylation suggested the ionic flux experiments reported here.…”

“…Our previous biochemical and biophysical studies suggested that the disease could be best understood as a cell membrane alteration with independent expression in several tissues (Roses & Appel, 1973; Butterfield, Chesnut, Roses & Appel, 1974a; Butterfield, Roses, Cooper, Appel & Chesnut, 1974b. ; Roses & Appel, 1974, 1975 Miller, . This concept has been supported by the findings of other investigators in a wide variety of human and murine muscular dystrophies.…”

Isolation of an abnormally phosphorylated erythrocyte membrane band 3 glycoprotein from patients with myotonic muscular dystrophy

“…The present studies represent one of a series of experiments using several lectins including Concanavalin A, Ricin II, and wheat germ agglutinin. None of these other lectins yielded a fraction that showed a difference in phosphorylation in MyD membranes as compared to controls (Roses, 1976).…”

“…The carbohydrate moieties of the major sialoglycoprotein have been shown to vary, depending on the age of the erythrocyte cells (Marikovsky, Danon & Katchalsky, 1966;Balduini & Ascari, 1974). Carbohydrate heterogeneity may also be an explanation for the Band 3 glycoprotein since affinity chromatography with the lectin, Concanavalin A (Roses, 1976;Findlay, 1974), and the binding of *25I-Concanavalin A to the electrophoretic region of migration of Band 3 (Kawaguchi & Osawa, 1976) have demonstrated that Concanavalin A can interact with only a fraction of Band 3 (approximately 30%). The use of galactose oxidase with tritiated sodium borohydride also indicated a carbohydrate heterogeneity in proteins of Band 3 since the peak of incorporation of tritium in the electrophoretic region of migration of isolated Band 3 lags slightly behind the Coomassie blue peak of Band 3 (Yu & Steck, 1975a).…”

Glycophorin and the concanavalin A receptor of human erythrocytes: their receptor function in lipid bilayers.

“…1 and references contained therein). Glycophorin is the human erythrocyte receptor for influenza virus and several lectins, and carries the M/N blood group determinants (2), while a subpopulation of band 3 is the concanavalin A (Con A) receptor (3,4).…”