PMID: 12575940

 

    Legend: Sugar

Title : Crystal structure of protein C inhibitor provides insights into hormone binding and heparin activation

Abstract :

1. Protein C inhibitor ( PCI ) is a member of the serpin family that has many biological functions
2. In blood it acts as a procoagulant, and, in the seminal vesicles, it is required for spermatogenesis
3. The activity of PCI is affected by heparin binding in a manner unique among the heparin binding serpins, and, in addition, PCI binds hydrophobic hormones with apparent specificity for retinoids
4. Here we present the 2.4 A crystallographic structure of reactive center loop ( RCL ) cleaved PCI
5. A striking feature of the structure is a two-turn N-terminal shortening of helix A, which creates a large hydrophobic pocket that docking studies indicate to be the retinoid binding site
6. On the basis of surface electrostatic properties, a novel mechanism for heparin activation is proposed