title: Histidine-rich glycoprotein is evolutionarily related to the cystatin superfamily. Presence of two cystatin domains in the N-terminal region.
abstract: A new member of the cystatin superfamily is introduced. Human plasma histidine-rich glycoprotein (HRG) was found to contain 2 cystatin-like sequences in tandem in the N-terminal region. Domain 1 (residues 1-112) was most homologous to domain 1 of the heavy chain of human kininogen and domain 2 (residues 113-225) was most homologous to human cystatin S as well as other cystatins and domain 3 of the heavy chain of kininogen, suggesting that the cystatin domains of HRG may represent a hitherto unknown binary form (or intermediate molecule) composed of 2 cystatin domains, and evolutionarily intermediate between the cystatin and the kininogen families.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D002417:Cattle; D002645:Chickens; D055313:Cystatin B; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D006801:Humans; D007704:Kininogens / Q000235:genetics; D005810:Multigene Family; D011480:Protease Inhibitors / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D051381:Rats; D055333:Salivary Cystatins; D012471:Salivary Proteins and Peptides / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D000099053:Histidine-Rich Glycoprotein
chemical_list: C525030:CST3 protein, human; C525173:CST4 protein, human; C524994:CSTB protein, human; C525032:Cst3 protein, rat; C525174:Cyss protein, rat; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D007704:Kininogens; D011480:Protease Inhibitors; D011506:Proteins; D055333:Salivary Cystatins; D012471:Salivary Proteins and Peptides; C100158:cystatin, egg-white; D000099053:Histidine-Rich Glycoprotein; D055313:Cystatin B