1HJX: Ligand-induced Signalling And Conformational Change Of The 39 Kd Glycoprotein From Human Articular Chondrocytes

The 39-kDa human cartilage glycoprotein (HCGP39), a member of a novel family of chitinase-like lectins (Chilectins), is overexpressed in articular chondrocytes and certain cancers. Proposed functions of this protein include a role in connective tissue remodeling and defense against pathogens. Similar to other Chi-lectins, HCGP39 promotes the growth of connective tissue cells. The ability of HCGP39 to activate cytoplasmic signaling pathways suggests the presence of a ligand for this protein at the cell surface. There is currently no information regarding the identity of any physiological or pathological ligands of the Chi-lectins or the nature of the protein-ligand interaction. Here, we show that HCGP39 is able to bind chitooligosaccharides with micromolar affinity. Crystal structures of the native protein and a complex with GlcNAc8 show that the ligand is bound in identical fashion to family 18 chitinases. However, unlike the chitinases, binding of the oligosaccharide ligand to HCGP39 induces a large conformational change. Thus, HCGP39 could be a lectin that binds chitin-like oligosaccharide ligands and possibly plays a role in innate responses to chitinous pathogens, such as fungi and nematodes.
PDB ID: 1HJXDownload
MMDB ID: 22267
PDB Deposition Date: 2003/2/28
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 1.85  Å
Source Organism:
Similar Structures:
Biological Unit for 1HJX: tetrameric; determined by author and by software (PQS)
Molecular Components in 1HJX
Label Count Molecule
Proteins (4 molecules)
Chitinase-3 Like Protein 1(Gene symbol: CHI3L1)
Molecule annotation
Chemicals (32 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB