Takayama Y, Takada F, Nowatari M, Kawakami M, Matsu-ura N
Department of Molecular Biology, Kitasato University School of Medicine, Kanagawa, Japan.
Mol Immunol. 1999 Jun;36(8):505-14. doi: 10.1016/s0161-5890(99)00070-x.
The Ra-reactive factor (RaRF) is a complement dependent anti-microbial factor that reacts with numerous microorganisms such as viruses, bacteria, fungi and protozoa. It is a complex of a mannan-binding lectin (MBL) and the serine protease, P100 (MASPI). P100 activates the C4 component of the complement system and its domain organization is similar to C1r and C1s. In this study, determination was made of the structure of the human P100 gene which was found longer than 67 kbp and to be comprised of 16 exons. Its non-protease region consisted of 10 exons, as in the case of C1r and C1s, and the introns were found present in the boundary separating two CUB domains, an EGF-like domain and two CCP domains and each CUB and CCP domain contained extra internal introns. The serine protease region was comprised of 6 exons in contrast to C1r and C1s, either of which consists of a single exon. The exon-intron structure was found to reflect the evolution of these molecules and P100 to have derived earlier in the stage of evolution than C1r or C1s.
类风湿反应因子（RaRF）是一种补体依赖性抗微生物因子，可与多种微生物发生反应，如病毒、细菌、真菌和原生动物。它是甘露聚糖结合凝集素（MBL）和丝氨酸蛋白酶P100（MASPI）的复合物。P100激活补体系统的C4成分，其结构域组织与C1r和C1s相似。在本研究中，对人P100基因的结构进行了测定，发现其长度超过67kbp，由16个外显子组成。其非蛋白酶区域由10个外显子组成，与C1r和C1s的情况相同，并且在内含子存在于分隔两个CUB结构域、一个EGF样结构域和两个CCP结构域的边界处，每个CUB和CCP结构域还包含额外的内部内含子。与C1r和C1s不同，丝氨酸蛋白酶区域由6个外显子组成，C1r和C1s均由单个外显子组成。外显子-内含子结构反映了这些分子的进化过程，并且发现P100在进化阶段比C1r或C1s更早起源。
