C1 FUNCTION ANALYZED WITH NATURALLY-OCCURRING INHIBITORS

当免疫复合物结合C1的C1q亚组分时，结合的C1q具有 两个重要的活动：1)提供C1r2s2的结合位点， C1的催化单位，激活补体级联的其余部分； 2)刺激具有C1q受体的细胞。总体目标 这一建议的目的是识别和表征天然的抑制物 C1，负责特定和受限的功能 C1在体内的活性。特别是，我们专注于两种抑制剂， 因子J和硫酸乙酰肝素，它们可能能够控制 回收结合的C1q作为Clr2s2的激活剂，并作为刺激 携带C1q受体的细胞。 J因子最初是从人的尿液和血清中分离出来的 在首席调查员的实验室里。它是一种高度糖基化的， 碱性蛋白质，由200,000，18,000和5,900个亚基组成，即 在一些循环细胞上表达。J因子与C1q结合，是一种有效的 从C1q组装大分子C1的非竞争性抑制剂 和C1r2s2亚组分。它在结构和功能上都是截然不同的 从其他已知的C1抑制剂中分离出来。J因子的蛋白质序列将 通过Edman降解或使用蛋白质水解物进行质谱分析来确定 脱糖蛋白的碎片。通过生产高滴度的多克隆 和单抗将有可能定义功能性和 该蛋白的抗原区，表征了J因子的表达 各种组织中的抗原，并进行生物合成研究。

When immune complexes bind the C1q subcomponent of C1, the bound C1q has two important activities: 1) providing a binding site for C1r2s2, the catalytic unit of C1, which activates the rest of the complement cascade; and 2) stimulating cells bearing the C1q receptor. The overall objectives of this proposal are to identify and characterize the natural inhibitors of C1, which are responsible for the specific and restricted functional activity of C1 in vivo. In particular, we are focusing on two inhibitors, Factor J and heparan sulfate, which are potentially able to control the recycling of bound C1q as an activator of Clr2s2, and as a stimulus to cells bearing C1q receptors. Factor J was initially identified and isolated from human urine and serum in the Principal Investigator's laboratory. It is a heavily glycosylated, basic protein, comprised of 200,000, 18,000, and 5,900 subunits, which is expressed on some circulating cells. Factor J binds to C1q and is a potent non-competitive inhibitor of the assembly of macromolecular C1 from the C1q and C1r2s2 subcomponents. It is structurally and functionally distinct from other known inhibitors of C1. The protein sequence of Factor J will be determined by Edman degradation or mass spectrometry using proteolytic fragments of deglycosylated protein. By producing high titer polyclonal and monoclonal antibodies it will be possible to define the functional and antigenic domains of the protein, characterize the expression of Factor J antigen in various tissues, and perform biosynthetic studies.