Margulies M M, Weistrop J S
Biochim Biophys Acta. 1980;606(1):20-33. doi: 10.1016/0005-2787(80)90094-5.
A sub-membrane fraction which contains a large portion of any thylakoid-bound ribosomes can be obtained when thylakoids are treated with the detergents Nonidet P-40, or Triton X-100. These 'pseudopolysome' fractions contain 50% of thylakoid-bound ribosomes, but less than 0.5% of thylakoid chlorophyll. Triton and Nonidet psuedopolysomes contain about 10%, and 3% of thylakoid protein, respectively. Pseudopolysomes, prepared from thylakoids with low levels of ribosomes, contain about the same proportion of thylakoid protein but proportionately less ribosomes. Pseudopolysomes contain thylakoid polypeptides in addition to chlorophyll, but lack a major membrane polypeptide of Mr 50 000. Pseudopolysome chlorophyll, and RNA band at the same buoyant density. However, they band at different densities after pseudopolysomes are treated with trypsin (a procedure which strips thylakoids of ribosomes). Pseudopolysome fractions from thylakoids with low levels of ribosomes have a lower density than the corresponding fractions from thylakoids with high levels of ribosomes. Ribosomes are released from thylakoids, and pseudopolysomes by the same treatments. Subunits are released with KCl and puromycin. Polysomes are released with trypsin. It was concluded the pseudopolysomes consist of ribosomes and a membrane fragment containing the sites to which ribosomes are bound.
当类囊体用去污剂Nonidet P - 40或Triton X - 100处理时，可以获得一种包含大部分类囊体结合核糖体的亚膜部分。这些“假多聚核糖体”部分含有50%的类囊体结合核糖体，但不到类囊体叶绿素的0.5%。Triton和Nonidet假多聚核糖体分别含有约10%和3%的类囊体蛋白。由核糖体含量低的类囊体制备的假多聚核糖体含有大致相同比例的类囊体蛋白，但核糖体比例相对较少。假多聚核糖体除了含有叶绿素外，还含有类囊体多肽，但缺少一种分子量为50000的主要膜多肽。假多聚核糖体叶绿素和RNA在相同的浮力密度下条带。然而，在用胰蛋白酶处理假多聚核糖体（一种从类囊体上剥离核糖体的方法）后，它们在不同的密度下条带。核糖体含量低的类囊体的假多聚核糖体部分的密度低于核糖体含量高的类囊体的相应部分。通过相同的处理从类囊体和假多聚核糖体中释放核糖体。亚基用KCl和嘌呤霉素释放。多聚核糖体用胰蛋白酶释放。得出的结论是，假多聚核糖体由核糖体和一个含有核糖体结合位点的膜片段组成。
