Harris R J, Wagner K L, Spellman M W
Department of Medicinal and Analytical Chemistry, Genentech, Inc., South San Francisco, CA 94080.
Eur J Biochem. 1990 Dec 12;194(2):611-20. doi: 10.1111/j.1432-1033.1990.tb15660.x.
CD4-IgG is a homodimer of a hybrid polypeptide consisting of the two amino-terminal domains (residues 1-180) of human CD4 fused to the hinge region and the second and third constant-sequence (CH2 and CH3) Fc domains (residues 216-441) of human immunoglobulin G (IgG-1). This antibody-like molecule, termed an immunoadhesin, was produced in an effort to combine the binding specificity of CD4 with several potentially desirable properties of IgG molecules [Capon et al. (1989) Nature 337, 525-531]. The structural characteristics of the molecule have been evaluated to demonstrate that CD4-IgG has the same features as the N-terminal region of soluble CD4, while retaining those expected for the Fc portion of human IgG. Identification of peptides recovered from the tryptic map confirmed 98.8% of the expected structure of CD4-IgG. The detection of glucosamine in peptides containing Asn257 and the retention time shift of this tryptic peptide after deglycosylation confirmed the presence of Asn-linked oligosaccharides at this position. Four pairs of intrachain and two interchain disulfide bonds were also established.
CD4-IgG是一种杂合多肽的同型二聚体，该杂合多肽由人CD4的两个氨基末端结构域（第1至180位氨基酸残基）与人免疫球蛋白G（IgG-1）的铰链区以及第二和第三恒定序列（CH2和CH3）Fc结构域（第216至441位氨基酸残基）融合而成。这种类似抗体的分子被称为免疫粘附素，它是为了将CD4的结合特异性与IgG分子的几种潜在理想特性结合而产生的[卡彭等人（1989年）《自然》337卷，525 - 531页]。对该分子的结构特征进行了评估，结果表明CD4-IgG具有与可溶性CD4的N端区域相同的特征，同时保留了人IgG的Fc部分所预期的那些特征。从胰蛋白酶图谱中回收的肽段鉴定结果证实了CD4-IgG预期结构的98.8%。在含有Asn257的肽段中检测到氨基葡萄糖，并且该胰蛋白酶肽段在去糖基化后的保留时间发生了变化，这证实了该位置存在Asn连接的寡糖。还确定了四对链内二硫键和两对链间二硫键。
