title: Erythrocytes contain cytoplasmic glycoproteins. O-linked GlcNAc on Band 4.1.
abstract: Previously we reported that the novel protein-saccharide linkage, O-linked N-acetylglucosamine (GlcNAc), is found in abundance on proteins associated with the cytoplasmic and nucleoplasmic faces of the nuclear pore complex. Here we demonstrate that O-GlcNAc moieties are also added to human erythrocyte cytoplasmic proteins. Intact or permeabilized erythrocytes, as well as subcellular fractions, were labeled with bovine milk galactosyltransferase and UDP-[3H] galactose. The proportion of the incorporated label found on O-GlcNAc was determined by a variety of chemical and enzymatic techniques. The bulk of the O-GlcNAc residues are found in the cytoplasm of erythrocytes, the majority of which are on an as yet unidentified 65-kDa protein. In addition, we have determined that Band 4.1, a protein which serves as a bridge joining the cytoskeleton to the inner surface of the plasma membrane in erythrocytes, also contains O-GlcNAc moieties. One of the sites of O-GlcNAc addition has been localized to the last 117 amino acids of the carboxy terminus of Band 4.1.
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis*; D001798:Blood Proteins / Q000302:isolation & purification / Q000378:metabolism*; D003593:Cytoplasm / Q000032:analysis; D003598:Cytoskeletal Proteins; D004912:Erythrocytes / Q000032:analysis*; D005700:Galactosyltransferases; D005944:Glucosamine / Q000031:analogs & derivatives*; D006023:Glycoproteins / Q000097:blood* / Q000302:isolation & purification; D006801:Humans; D008565:Membrane Proteins; D008970:Molecular Weight; D009479:Neuropeptides
chemical_list: D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D006023:Glycoproteins; D008565:Membrane Proteins; D009479:Neuropeptides; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D005700:Galactosyltransferases; D005944:Glucosamine; D000117:Acetylglucosamine