Biological functions of novel human plasma proteins, IHRP and PHBP.

本研究试图阐明我们分别于1994年和1995年发现的新的人血浆蛋白IHRP和PHBP的生物学功能。JHRP的研究（1）蛋白质结构：人JHRP是一种约900个氨基酸的单链多肽。克隆了猪和小鼠的IHRP cDNA，其氨基酸序列同源性在三个物种之间约为70%。从三种动物中获得的所有IHRP都有一个对蛋白酶敏感的位点。(2)基因组结构：人IHRP基因组由24个外显子组成，与α-胰蛋白酶间抑制剂重链的外显子同源。(3)功能分析：虽然牛IHRP已被报道为典型的急性时相蛋白，但人IHRP的血浆浓度在炎症条件下并不增加。在小鼠中，诱导炎症后IHRP在肾脏中沉积，并且膜联蛋白参与沉积. PHBP的研究（1）蛋白质结构：克隆了人和小鼠PHBP的cDNA。两种PHBPs的氨基酸序列同源性达70%。(2)基因组结构：人PHBP基因组由13个外显子组成，与凝血因子XII基因组结构相似。（3）功能分析：PHBP是一种丝氨酸蛋白酶，特异性切割精氨酸残基C端的肽键。PHBP是在正常条件下不显示蛋白水解活性的单链多肽，并且通过在特定位置处的切割而被激活。

We tried to elucidate biological functions of novel human plasma proteins, IHRP and PHBP, discovered by us in 1994 and 1995, respectively.1. Study on JHRP(1) Protein structure : human JHRP is a single chain polypeptide of about 900 amino acids. Porcine and mouse IHRP cDNAs were cloned, the amino acid sequence homology was about 70% among all the three species. All IHRPs obtained from the three animal species had a site susceptible to proteases. (2) Genomic structure : human IHRP genome was composed of 24 exons, and homologous to that of the heavy chain of inter-aipha-trypsin inhibitor. (3) Functional analysis : although bovine IHRP has been reported to be a typical acute phase protein, the plasma concentration of humam IHRP did not inrease under inflammation conditions. In mice, IHRP was deposited in the kidney after the induction of inflammation and an annexin was involved in the deposition.2. Study on PHBP(1) Protein structure : human and mouse PHBP cDNAs were cloned. The two PHBPs showed a 70% homology in amino acid sequence. (2) Genomic structure : human PHBP genome was composed of 13 exons, and significantly similar to that of the coagulation factor XII.(3)functional analysis : PHBP was a serine protease that specically cleaved the peptide bond at C-terminal side of Arg residue. PHBP is a single chain polypeptide that shows no proteolytic activity under normal conditions, and is activated by the cleavage at a specific position.