3TJN: Htra1 Catalytic Domain, Apo Form

The homotrimeric human serine protease HtrA1 is homologous to bacterial HtrA proteases regarding the trypsin-like catalytic and PDZ domains but differs by the presence of an N-terminal domain with IGFBP and Kazal homology. The crystal structures and SAXS analysis presented herein reveal the rare tandem of IGFBP- and Kazal-like modules, a protease active site that adopts a competent conformation in the absence of substrate or inhibitor and a model for the intact protein in solution. Highly sensitive enzymatic assays and binding studies demonstrate that the N-terminal tandem has no apparent effect on protease activity, and in accordance with the structure-based predictions, neither the IGFBP- nor Kazal-like module retains the function of their prototype proteins. Our structures of the unliganded HtrA1 active site suggest two-state equilibrium and a "conformational selection" model, in which substrate binds to the active conformer.
PDB ID: 3TJNDownload
MMDB ID: 99659
PDB Deposition Date: 2011/8/24
Updated in MMDB: 2012/06
Experimental Method:
x-ray diffraction
Resolution: 3  Å
Source Organism:
Similar Structures:
Biological Unit for 3TJN: trimeric; determined by author and by software (PISA)
Molecular Components in 3TJN
Label Count Molecule
Proteins (3 molecules)
Serine Protease Htra1(Gene symbol: HTRA1)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB