title: Structural and functional characterization of a novel tumor-derived rat galectin-1 having transforming growth factor (TGF) activity: the relationship between intramolecular disulfide bridges and TGF activity.
abstract: Previously we demonstrated that overexpression of a beta-galactoside binding protein, galectin-1, caused the transformation of BALB3T3 fibroblast cells [Yamaoka, K., Ohno, S., Kawasaki, H., and Suzuki, K. (1991) Biochem. Biophys. Res. Commun. 179, 272-279]. We have now studied the structure-function relationship between the sugar-binding activity and the mitogenic activity of galectin-1 purified from an avian sarcoma virus-transformed rat NRK cell line, 77N1. The purified galectin-1 (t-galectin-1) had potent mitogenic activity in BALB3T3 cells, but no sugar-binding activity. Treatment of t-galectin-1 with 2-mercaptoethanol decreased its mitogenic activity, but resulted in the appearance of a sugar binding activity. Chemical modification of sulfhydryl groups in purified t-galectin-1 with [14C]-iodoacetamide suggested the presence of intramolecular disulfide bonds. MALDI-TOF mass spectrometric analysis of the native and reduced forms of the tryptic peptides from t-galectin-1 showed that t-galectin-1 has two intramolecular disulfide bonds (Cys2-Cys16 and Cys42-Cys60). These studies suggest that these intramolecular disulfide bonds of t-galectin-1 are essential for its mitogenic activity and that the different activities may be regulated by structural changes caused by intramolecular disulfide bond-breakage.
authors.affiliation: Department of Biochemical Cell Research, Tokyo Metropolitan Institute of Medical Science. yamaoka@rinshoken.or.jp
authors.forename: K
authors.initials: K
authors.lastname: Yamaoka
authors.forename: A
authors.initials: A
authors.lastname: Ingendoh
authors.forename: S
authors.initials: S
authors.lastname: Tsubuki
authors.forename: Y
authors.initials: Y
authors.lastname: Nagai
authors.forename: Y
authors.initials: Y
authors.lastname: Sanai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001212:Asialoglycoproteins / Q000378:metabolism; D001358:Avian Sarcoma Viruses / Q000235:genetics / Q000378:metabolism; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D004279:DNA, Viral / Q000096:biosynthesis; D004229:Dithiothreitol / Q000494:pharmacology; D060748:Fetuins; D037483:Galectin 1; D006388:Hemagglutinins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007460:Iodoacetamide / Q000737:chemistry; D037102:Lectins / Q000737:chemistry* / Q000494:pharmacology; D013058:Mass Spectrometry; D008623:Mercaptoethanol / Q000494:pharmacology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011485:Protein Binding; D051381:Rats; D015291:Transforming Growth Factors; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D000906:Antibodies; D001212:Asialoglycoproteins; D004279:DNA, Viral; D060748:Fetuins; D037483:Galectin 1; D006388:Hemagglutinins; D037102:Lectins; D000509:alpha-Fetoproteins; C017029:asialofetuin; D008623:Mercaptoethanol; D015291:Transforming Growth Factors; D004229:Dithiothreitol; D007460:Iodoacetamide