Human MRP14

Summary

Human MRP14 (hMRP14) is a Ca²⁺-binding protein from the S100 family of proteins. This protein is co-expressed with human MRP8 (hMRP8), a homologue protein in myeloid cells, and plays an indispensable role in Ca²⁺-dependent functions during inflammation. This role includes the activation of Mac-1, the β₂ integrin which is involved in neutrophil adhesion to endothelial cells.
The crystal structure of the holo form of hMRP14 was analyzed at 2.1 Å resolution. hMRP14 is distinguished from other S100 member proteins by its long C-terminal region, and its structure shows that the region is extensively flexible. In this crystal structure of hMRP14, CHAPS molecules bind to the hinge region that connects two EF-hand motifs, which suggests that this region is a target-binding site of this protein. Based on a structural comparison of hMRP14 with hMRP8 and human S100A12 (hS100A12) that is another homologue protein, the character of MRP8/14 hetero-complex and the functional significance of the flexibility of the C-terminal region of hMRP14 are revealed.

Figure Caption

The ribbon representation of human MRP14 dimer. Dotted lines show the direction of flexible C-terminal loop region. Yellow balls indicating calcium-ions. The bound CHAPS molecule is drawn in green ball and stick model.

References

• The Crystal Structure of Human MRP14 (S100A9), a Ca²⁺-dependent Regulator Protein in Inflammatory Process
  Hiroshi Itou, Min Yao, Ikuko Fujita, Nobuhisa Watanabe, Masaki Suzuki, Jun Nishihira and Isao Tanaka
  J. Mol. Biol. (2002) 316, 265-276
  
  
• Expression, purification, crystallization and preliminary X-ray diffraction analysis of the human calcium-binding protein MRP14 (S100A9)
  Hiroshi Itou, Ikuko Fujita, Kohtaro Ishikawa, Min Yao, Nobuhisa Watanabe, Masaki Suzuki, Jun Nishihira and Isao Tanaka
  Acta Cryst. (2001) D57, 1174-1176