McCurdy D W, Williamson R E
Research School of Biological Sciences, Australian National University, Canberra City, ACT.
J Cell Sci. 1987 Apr;87 ( Pt 3):449-56. doi: 10.1242/jcs.87.3.449.
A pea chloroplast protein resembles vertebrate and algal actins by several chemical and immunological criteria. On two-dimensional polyacrylamide gels it migrated with a slightly lower relative molecular mass (Mr = 41,000) and slightly more basic isoelectric point than rabbit skeletal muscle actin. A monoclonal antibody to chicken gizzard actin reacted on immunoblots with rabbit skeletal actin, with Chara actin and with a 41,000 Mr band from pea chloroplasts. Pea and Chara bands of approximately 58,000 Mr were also stained. A DNase I-affinity column that bound muscle actin also bound 41,000 and 58,000 Mr chloroplast polypeptides. Similarities existed between enzymically and chemically generated fragments of the 41,000 Mr chloroplast polypeptide and rabbit muscle actin. The 41,000 Mr protein was protected from degradation by thermolysin only in preparations of intact, but not ruptured, isolated chloroplasts, indicating that this protein resides within the outer envelope membrane of these organelles. It is concluded that a 41,000 Mr protein with major similarities to actin occurs inside pea chloroplasts, and that a 58,000 Mr protein with some similarities to actin also probably exists within chloroplasts.
根据多种化学和免疫学标准，一种豌豆叶绿体蛋白与脊椎动物及藻类的肌动蛋白相似。在二维聚丙烯酰胺凝胶上，它的迁移相对分子质量略低（Mr = 41,000），等电点比兔骨骼肌肌动蛋白略偏碱性。一种针对鸡砂囊肌动蛋白的单克隆抗体在免疫印迹中能与兔骨骼肌肌动蛋白、轮藻肌动蛋白以及豌豆叶绿体中一条相对分子质量为41,000的条带发生反应。豌豆和轮藻中相对分子质量约为58,000的条带也被染色。一个能结合肌肉肌动蛋白的DNA酶I亲和柱也能结合相对分子质量为41,000和58,000的叶绿体多肽。相对分子质量为41,000的叶绿体多肽经酶解和化学裂解产生的片段与兔肌肉肌动蛋白之间存在相似性。只有在完整而非破裂的分离叶绿体制剂中，相对分子质量为41,000的蛋白质才能免受嗜热菌蛋白酶的降解，这表明该蛋白质位于这些细胞器的外被膜内。得出的结论是，豌豆叶绿体内部存在一种与肌动蛋白有主要相似性的相对分子质量为41,000的蛋白质，并且叶绿体中可能还存在一种与肌动蛋白有一些相似性的相对分子质量为58,000的蛋白质。
