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

• Published in: Journal of biochemistry (Tokyo) Vol. 119; no. 5; pp. 878 - 886
• Main Authors: Yamaoka, Kazuko, Ingendoh, Arnd, Tsubuki, Satoshi, Nagai, Yoshitaka, Sanai, Yutaka
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.05.1996
• Subjects: alpha-Fetoproteins - metabolism; Amino Acid Sequence; Animals; Antibodies - immunology; Asialoglycoproteins - metabolism; Avian Sarcoma Viruses - genetics; Avian Sarcoma Viruses - metabolism; BALB3T3; Cell Line, Transformed; Cell Transformation, Neoplastic; disulfide bond; Dithiothreitol - pharmacology; DNA, Viral - biosynthesis; Fetuins; galectin; Galectin 1; Hemagglutinins - chemistry; Hemagglutinins - immunology; Hemagglutinins - metabolism; Hemagglutinins - pharmacology; Humans; Iodoacetamide - chemistry; Lectins - chemistry; Lectins - pharmacology; MALDI-TOF; Mass Spectrometry; Mercaptoethanol - pharmacology; Molecular Sequence Data; Molecular Weight; Protein Binding; Rats; transforming growth factor; Transforming Growth Factors
• ISSN: 0021-924X
• DOI: 10.1093/oxfordjournals.jbchem.a021325

Previously we demonstrated that overexpression of a β-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 relationships between the sugar-binding activity and the mitogenic activity of galectin-1 purified from an avian sarcoma virus-transformed rat NKK 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-mercap-toethanol 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-Cysl6 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.