IDENTIFICATION OF 2 NUCLEAR N-ACETYLGLUCOSAMINE-BINDING PROTEINS

Using neoglycoproteins, lectins that recognize different sugars, inclu ding N-acetylglucosamine residues, were previously detected in animal cell nuclei. We report herein the isolation of two N-acetylglucosamine -binding proteins from HL60 cell nuclei: i) a 22 kDa polypeptide (CBP2 2) with an isoelectric point of 4.5 was isolated for the first time an d ii) a 70 kDa polypeptide with an isoelectric point of 7.8. This latt er protein corresponds to the glucose-binding protein (CBP70) previous ly isolated, based on the following similarities: i) they have the sam e molecular mass, ii) they have the same isoelectric point, iii) they are recognized by antibodies raised against CBP70, and iv) both are le ctins from the C group of Drickamer's classification. CBP70 appeared t o recognize glucose and N-acetylglucosamine; however, its affinity for N-acetylglucosamine was found to be twice that for glucose. The prese nce in the nucleus of two nuclear N-acetylglucosamine-binding proteins and their potential ligands, such as O-N-acetylglucosamine glycoprote ins, strongly argues for possible intranuclear glycoprotein-lectin int eractions. (C) 1994 Wiley-Liss, Inc.