Kwak K B, Lee Y S, Suh S W, Chung C S, Ha D B, Chung C H
Department of Zoology, College of Natural Sciences, Seoul National University, Korea.
Exp Cell Res. 1989 Aug;183(2):501-7. doi: 10.1016/0014-4827(89)90409-6.
Purothionin from wheat endosperm is a cysteine-rich, basic polypeptide of about 5000 Da, which modifies membrane permeability of cultured mammalian cells. This peptide was found to block fusion of chick embryonic muscle cells in culture but allows proliferation and alignment. A purothionin concentration of 6 micrograms/ml (1.2 microM) was necessary for the complete prevention of myotube formation. Under similar conditions, incorporation of [35S]methionine occurred normally but the synthesis of muscle-specific proteins including creatine kinase and acetylcholine receptor was strongly inhibited. In addition, purothionin blocked the uptake of 86Rb+, immediately after its addition to the cultured myoblasts. No such effects were found with the purothionin chemically modified with acetic or succinic anhydride. Thus, the basic residues in purothionin appear to be associated with the inhibition of myogenic differentiation. These results suggest that purothionin exerts its regulatory effect on the transition from proliferative to differentiative myoblasts by interfering with membrane permeability or intercellular contact and recognition, which are necessary for the initiation of muscle differentiation.
从小麦胚乳中提取的硫堇蛋白是一种富含半胱氨酸的碱性多肽，分子量约为5000道尔顿，它能改变培养的哺乳动物细胞的膜通透性。已发现该肽可阻断培养的鸡胚肌肉细胞的融合，但能使其增殖并排列整齐。硫堇蛋白浓度为6微克/毫升（1.2微摩尔）时，才能完全阻止肌管形成。在类似条件下，[35S]甲硫氨酸的掺入正常，但包括肌酸激酶和乙酰胆碱受体在内的肌肉特异性蛋白的合成受到强烈抑制。此外，硫堇蛋白加入培养的成肌细胞后，会立即阻断86Rb+的摄取。用乙酸酐或琥珀酸酐化学修饰的硫堇蛋白未发现此类作用。因此，硫堇蛋白中的碱性残基似乎与抑制肌源性分化有关。这些结果表明，硫堇蛋白通过干扰膜通透性或细胞间接触与识别，对增殖性成肌细胞向分化性成肌细胞的转变发挥调节作用，而膜通透性或细胞间接触与识别是肌肉分化起始所必需的。
