Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

Biochem J. 2016 Jan 1;473(1):31-42. doi: 10.1042/BJ20150843. Epub 2015 Oct 20.


Transglutaminase-2 (TG2) is best known as a Ca(2+)-dependent cross-linking enzyme; however, some of its extracellular matrix-related functions are independent of its catalytic activity and include matrix remodelling, adhesion and migration. S100A4 belongs to the Ca(2+)-binding EF-hand S100 protein family and acts both intra- and extra-cellularly through binding to various partners. It regulates cell migration and its overexpression is strongly associated with metastasis and poor survival in various cancers. It has recently been suggested that TG2 mediates S100A4-dependent tumour cell migration. In the present study we provide evidence that S100A4 is an interacting partner and also a specific amine donor of TG2. TG2 incorporates a glutamine donor peptide to Lys(100) in the C-terminal random coil region of S100A4. Importantly, the enzyme activity is not necessary for the interaction: S100A4 also binds to TG2 in the presence of a specific inhibitor that keeps the enzyme in an open conformation, or to an enzymatically inactive mutant. We also found that S100A4 considerably enhances TG2-mediated adhesion of A431 epithelial carcinoma cells to the extracellular matrix. This role is independent of enzyme activity and requires the open conformation of TG2. We propose that S100A4 stabilizes the open conformation of TG2, which binds to its cell-surface receptor in this state and increases cell adhesion.

Keywords: S100 proteins; S100A4; cell adhesion; metastasis; protein cross-linking; transglutaminase-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amines / metabolism*
  • Amino Acid Sequence
  • Cell Line, Tumor
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Neoplasm Metastasis* / genetics
  • Protein Binding / physiology
  • S100 Calcium-Binding Protein A4
  • S100 Proteins / genetics
  • S100 Proteins / metabolism*
  • Substrate Specificity / physiology
  • Transglutaminases / genetics
  • Transglutaminases / metabolism*


  • Amines
  • S100 Calcium-Binding Protein A4
  • S100 Proteins
  • S100A4 protein, human
  • transglutaminase 2
  • Transglutaminases
  • GTP-Binding Proteins