CROSS-LINKING OF GALECTIN-3, A GALACTOSE-BINDING PROTEIN OF MAMMALIAN-CELLS, BY TISSUE-TYPE TRANSGLUTAMINASE

The 30 kDa beta-galactoside-binding protein of baby hamster kidney (BH K) cells [Mehul et al. (1994), J. Biol. Chem. 269, 18250-18258] homolo gous to galectin 3, a widely distributed mammalian lectin, has been fo und to be a substrate for tissue type transglutaminase, as shown by th e incorporation in a calcium- and time-dependent manner of 5-(biotinam ido) pentylamine in the presence of guinea pig liver transglutaminase, The amino-terminal domain of hamster galectin 3, which is a repetitiv e sequence rich in glutamine, tyrosine, glycine and proline, is also a n excellent substrate, A single lysine residue in the N-terminal domai n is an essential requirement for transglutaminase-mediated oligomeriz ation, and two equivalent glutamine residues present in identical sequ ence repeats within this domain appear to be involved as amine accepte rs in cross-linking reactions. Transglutaminase-mediated cross-linking of galectin 3 to itself or to matrix components may be one mechanism for stablisation of a multivalent binding form of the lectin in cell s ecretions or in extracellular matrices,