Takada F, Takayama Y, Hatsuse H, Kawakami M
Department of Pediatrics, Kitasato University School of Medicine, Kanagawa-ken, Japan.
Biochem Biophys Res Commun. 1993 Oct 29;196(2):1003-9. doi: 10.1006/bbrc.1993.2349.
The Ra-reactive factor (RaRF) found in vertebrate sera activates the C4 and C2 components of complement. The C4/C2-activating component of mouse RaRF has been found to contain a 100-kDa serine protease called P100. In the present study, we cloned a cDNA with cDNA of mouse RaRF P100 as a probe from a human liver cDNA library. An open reading frame of 2097 nucleotides encoding a protein of 699 residues was found in the cloned cDNA of 4489 nucleotides. This protein exhibits 87.4% amino acid homology with mouse P100, and 36.4% and 37.1% homologies with that of the C1r and C1s subcomponents of human complement, respectively. The characteristic nodules and domain of C1r and C1s were highly conserved in this protein. This indicates that the P100, together with the C1r and C1s, forms a unique protein family having the same module/domain constitution.
在脊椎动物血清中发现的Ra反应因子（RaRF）可激活补体的C4和C2成分。已发现小鼠RaRF的C4/C2激活成分含有一种名为P100的100 kDa丝氨酸蛋白酶。在本研究中，我们以小鼠RaRF P100的cDNA为探针，从人肝脏cDNA文库中克隆了一个cDNA。在4489个核苷酸的克隆cDNA中发现了一个2097个核苷酸的开放阅读框，编码一个699个残基的蛋白质。该蛋白质与小鼠P100的氨基酸同源性为87.4%，与人类补体C1r和C1s亚成分的同源性分别为36.4%和37.1%。C1r和C1s的特征性结节和结构域在该蛋白质中高度保守。这表明P100与C1r和C1s一起形成了一个具有相同模块/结构域组成的独特蛋白质家族。
