Schematic representation of protein domains, posttranslational modifications, and proposed binding partners of human HRG. HRG is a multidomain protein consisting of 2 cystatin-like regions at the N-terminus (N1 and N2), a central histidine-rich region (HRR), 2 proline-rich regions (PRR1 and PRR2) flanking the HRR, and a C-terminal domain (C). Proposed carbohydrate attachment sites, disulfide bridges, binding partners of HRG, and the corresponding binding regions of HRG (ie, N1N2, HRR, or C) are depicted in the figure. Note that the binding sites for phospholipids, heparanase, fibrinogen, DNA, and certain complement components on HRG have not been characterized.