Osheroff P L, Tsai S P, Chiang N Y, King K L, Li R, Lewis G D, Wong K, Henzel W, Mather J
Department of Protein Chemistry, Genentech, Inc., South San Francisco, CA 94080, USA.
Growth Factors. 1999;16(3):241-53. doi: 10.3109/08977199909002133.
Sensory and motor neuron-derived factor (SMDF) is a member of the neuregulin family of proteins. SMDF is structurally characterized by a novel N-terminal domain. Using the signal sequence and N-terminal 28 amino acids (the "epitope") of herpes simplex virus type 1 glycoprotein D (gD), we have expressed SMDF as an epitope-tagged protein (gD-SMDF) in 293 cells, and purified it to > 98% homogeneity on a monoclonal anti-gD column. gD-SMDF stimulates human Schwann cell growth and 3H-thymidine incorporation in MCF-7 and T47D human breast tumor cells in vitro. The biological activity of gD-SMDF is consistent with its ability to compete with 125I-labeled heregulinbeta1 peptide (rHRGbeta1(177-244)) to bind to soluble dimeric ErbB receptor-IgG fusion proteins. gD-SMDF binds with low affinity to homodimeric ErbB3-IgG and ErbB4-IgG but with higher affinity to heterodimeric ErbB2/ErbB3-IgG and ErbB2/ErbB4-IgG. Using a SMDF-IgG(Fc) fusion protein we generated a monoclonal antibody (3G11) which binds SMDF, crossreacts with rHRGbeta1(177-244), and neutralizes the in vitro activities of gD-SMDF and rHRGbeta1(177-244) in human Schwann cells.
感觉和运动神经元衍生因子（SMDF）是神经调节蛋白家族的成员。SMDF在结构上的特征是具有一个新的N端结构域。利用1型单纯疱疹病毒糖蛋白D（gD）的信号序列和N端28个氨基酸（“表位”），我们在293细胞中表达了作为表位标记蛋白（gD-SMDF）的SMDF，并在单克隆抗gD柱上纯化至纯度>98%。gD-SMDF在体外刺激人雪旺细胞生长以及MCF-7和T47D人乳腺肿瘤细胞中3H-胸腺嘧啶核苷掺入。gD-SMDF的生物学活性与其与125I标记的神经调节蛋白β1肽（rHRGβ1(177 - 244)）竞争结合可溶性二聚体ErbB受体-IgG融合蛋白的能力一致。gD-SMDF与同二聚体ErbB3-IgG和ErbB4-IgG的结合亲和力较低，但与异二聚体ErbB2/ErbB3-IgG和ErbB2/ErbB4-IgG的结合亲和力较高。利用SMDF-IgG(Fc)融合蛋白，我们制备了一种单克隆抗体（3G11），它能结合SMDF，与rHRGβ1(177 - 244)交叉反应，并中和gD-SMDF和rHRGβ1(177 - 244)在人雪旺细胞中的体外活性。
