Galectin-3 is a nuclear matrix protein which binds RNA.
The endogenous galectin-3 is a carbohydrate-binding protein of M(r) approximately 30,000 serving in the cytoplasm and on the cell surface as a receptor for ligands containing poly-N-acetyllactosamine sequences. In addition, galectin-3 has been demonstrated to be associated in the nucleus with ribonucleoprotein complexes and to act as a pre-mRNA splicing factor and to be involved in spliceosome assembly. However, little is known about either its nuclear localization or its ligand(s), respectively. We demonstrate directly here that galectin-3 is associated with the RNA protein skeleton of the nucleus, i.e., the nuclear matrix, and binds with single-stranded DNA (ssDNA) and with RNA. The affinity of binding was determined to be 2.3 microM. Lactose, which inhibits galectin-3 binding to glycoconjugates, failed to inhibit either galectin-3-ssDNA or galectin-3-RNA binding. Galectin-3 exhibited the highest affinity to poly(A) ribonucleotide homopolymers. The results presented here shows that galectin-3 may act as a RNA-binding protein in the nuclear matrix in a non-carbohydrate-dependent manner.
Tumor Progression and Metastasis, karmanos Cancer Institute, Detroit, MI 48201, USA.
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Inohara
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Pienta
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D000818:Animals; D000943:Antigens, Differentiation / Q000737:chemistry / Q000378:metabolism*; D034961:Antigens, Nuclear; D004277:DNA, Single-Stranded / Q000378:metabolism; D037502:Galectin 3; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D015394:Molecular Structure; D009005:Monosaccharides / Q000494:pharmacology; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000943:Antigens, Differentiation; D034961:Antigens, Nuclear; D004277:DNA, Single-Stranded; D037502:Galectin 3; D009005:Monosaccharides; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D011061:Poly A; D012313:RNA