Thompson S A, Higashiyama S, Wood K, Pollitt N S, Damm D, McEnroe G, Garrick B, Ashton N, Lau K, Hancock N
Scios Nova Inc., Mountain View, California 94043.
J Biol Chem. 1994 Jan 28;269(4):2541-9.
Heparin-binding (HB) epidermal growth factor (EGF)-like growth factor (HB-EGF), a member of the EGF protein family, is a potent mitogen for fibroblasts, smooth muscle cells, and keratinocytes that was initially identified as a secreted product of macrophage-like cells. HB-EGF and EGF appear to act on target cells utilizing the same receptor, but HB-EGF is distinguishable from EGF by its strong affinity for heparin. To facilitate studies of structure-function relationships in HB-EGF, a bacterial recombinant expression system was established that produced biologically active HB-EGF with the expected disulfide bonding pattern. Mutagenesis and protease digestion studies of the recombinant HB-EGF, coupled with heparin-binding analyses of synthetic peptides, indicated that the sequences within HB-EGF mediating its interaction with heparin are located primarily in a stretch of 21 amino acids characterized by a high content of lysine and arginine residues. Most of this heparin-binding domain lies in an amino-terminal region of HB-EGF that has no counterpart in EGF, but a portion of the 21-residue sequence extends into the EGF-like region of HB-EGF. In addition, the mutagenesis and synthetic peptide studies indicated that sequences in HB-EGF lying outside of the 21-residue stretch can also influence the interaction with heparin. Finally, a synthetic peptide derived from the 21-residue stretch was found to compete with HB-EGF for binding to Chinese hamster ovary cells, suggesting that the heparin-binding sequences in HB-EGF may also mediate the interaction of this factor with cell surface heparan sulfate proteoglycan.
肝素结合（HB）表皮生长因子（EGF）样生长因子（HB-EGF）是EGF蛋白家族的一员，是一种对成纤维细胞、平滑肌细胞和角质形成细胞有强大作用的促有丝分裂原，最初被鉴定为巨噬细胞样细胞的分泌产物。HB-EGF和EGF似乎利用相同的受体作用于靶细胞，但HB-EGF因其对肝素的强亲和力而与EGF不同。为了便于研究HB-EGF的结构-功能关系，建立了一种细菌重组表达系统，该系统产生具有预期二硫键模式的生物活性HB-EGF。对重组HB-EGF的诱变和蛋白酶消化研究，以及对合成肽的肝素结合分析表明，HB-EGF中介导其与肝素相互作用的序列主要位于一段21个氨基酸的区域，其特征是赖氨酸和精氨酸残基含量高。这个肝素结合结构域的大部分位于HB-EGF的氨基末端区域，该区域在EGF中没有对应部分，但21个残基序列的一部分延伸到HB-EGF的EGF样区域。此外，诱变和合成肽研究表明，HB-EGF中位于21个残基延伸区之外的序列也会影响与肝素的相互作用。最后，发现从21个残基延伸区衍生的合成肽能与HB-EGF竞争结合中国仓鼠卵巢细胞，这表明HB-EGF中的肝素结合序列也可能介导该因子与细胞表面硫酸乙酰肝素蛋白聚糖的相互作用。
