L-29, an endogenous lectin, binds to glycoconjugate ligands with positive cooperativity

Biochemistry. 1993 Jan 12;32(1):260-7. doi: 10.1021/bi00052a033.

Abstract

The soluble mammalian lactose-binding lectins L-14-I and L-29 are both secreted and bind to oligosaccharides on laminin, a large extracellular matrix glycoprotein containing polylactosamine chains. Because of the potential functional significance of these lectin-laminin interactions, we compared quantitative aspects of L-14-I and L-29 binding to immobilized laminin using recombinant lectins labeled with 125I. We report that the concentration-dependent binding of L-29 exhibits positive cooperativity whereas binding of L-14-I does not. Cooperative binding of L-29 can also occur on glycoconjugate substrates other than laminin and is not dependent on cystine bond formation or aggregation in solution. L-29 contains repetitive sequences within the N-terminal domain not present in L-14-I. This domain is not required for binding activity, but is required for positive cooperativity. Though the precise mechanism of interaction of L-29 with laminin remains to be determined, it apparently results in assembly of a lectin aggregate on the substrate surface, which could have important functional consequences.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Differentiation / chemistry
  • Antigens, Differentiation / genetics
  • Antigens, Differentiation / metabolism*
  • Base Sequence
  • Binding Sites
  • Collagenases / metabolism
  • Dithiothreitol / pharmacology
  • Escherichia coli / genetics
  • Galectin 3
  • Glycoconjugates / metabolism*
  • Iodine Radioisotopes
  • Lactose / metabolism
  • Laminin / metabolism*
  • Mercaptoethanol / pharmacology
  • Molecular Sequence Data
  • Molecular Weight
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Rats
  • Recombinant Proteins / metabolism
  • Repetitive Sequences, Nucleic Acid

Substances

  • Antigens, Differentiation
  • Galectin 3
  • Glycoconjugates
  • Iodine Radioisotopes
  • Laminin
  • Peptide Fragments
  • Recombinant Proteins
  • Mercaptoethanol
  • Collagenases
  • Lactose
  • Dithiothreitol