Heldin C H, Johnsson A, Wennergren S, Wernstedt C, Betsholtz C, Westermark B
Nature. 1986;319(6053):511-4. doi: 10.1038/319511a0.
Platelet-derived growth factor (PDGF), as purified from fresh human platelets, is a protein of relative molecular mass (Mr) 30,000 composed of two disulphide-linked subunit chains of similar size, named A and B (ref. 1). The dimer structure of PDGRF seems to be important for its biological effects, as reduction irreversibly inactivates the factor; it is not known, however, whether PDGF exists as a heterodimer or as a mixture of homodimers. Amino-acid sequence analysis has revealed that the A- and B-chains of human PDGF are related to each other, and that the B-chain is almost identical to part of the v-sis gene product of simian sarcoma virus (SSV). There is experimental evidence that a PDGF-like protein is indeed operational in SSV-induced transformation and the biologically active v-sis product is probably structurally similar to a putative dimer of PDGF B-chains. PDGF-like growth factors and/or a 4.2-kilobase (kb) c-sis transcript are present in several transformed mammalian cell lines and in certain nontransformed cells; cloned c-sis complementary DNA from human T cells transformed with human T-lymphotropic virus (HTLV) or from human endothelial cells contains the coding sequence for a putative PDGF B-chain precursor, but apparently lacks PDGF A-chain sequences. We have previously partially purified and characterized a PDGF-like growth factor from U-2 OS cells (osteosarcoma-derived growth factor, ODGF) and shown that this factor has structural, functional and immunological characteristics in common with PDGF. We describe here a procedure for the preparation of homogeneous ODGF, and provide evidence that this factor, which binds to the PDGF receptor, has a structure similar to a homodimer of PDGF A-chains.
从新鲜人血小板中纯化得到的血小板源性生长因子（PDGF）是一种相对分子质量（Mr）为30,000的蛋白质，由两条大小相似的通过二硫键连接的亚基链组成，分别命名为A链和B链（参考文献1）。PDGRF的二聚体结构似乎对其生物学效应很重要，因为还原会不可逆地使该因子失活；然而，尚不清楚PDGF是以异二聚体形式存在还是以同二聚体混合物形式存在。氨基酸序列分析表明，人PDGF的A链和B链彼此相关，并且B链几乎与猿猴肉瘤病毒（SSV）的v-sis基因产物的一部分相同。有实验证据表明，一种类似PDGF的蛋白质确实在SSV诱导的转化中起作用，并且具有生物学活性的v-sis产物在结构上可能类似于PDGF B链的假定二聚体。几种转化的哺乳动物细胞系和某些未转化的细胞中存在类似PDGF的生长因子和/或4.2千碱基（kb）的c-sis转录本；从用人嗜T淋巴细胞病毒（HTLV）转化的人T细胞或人内皮细胞中克隆的c-sis互补DNA包含假定的PDGF B链前体的编码序列，但显然缺乏PDGF A链序列。我们之前已从U-2 OS细胞（骨肉瘤衍生生长因子，ODGF）中部分纯化并鉴定了一种类似PDGF的生长因子，并表明该因子具有与PDGF相同的结构、功能和免疫学特征。我们在此描述了一种制备均一ODGF的方法，并提供证据表明该与PDGF受体结合的因子具有与PDGF A链同二聚体相似的结构。
