Simpson D J
Eur J Cell Biol. 1983 Sep;31(2):305-14. doi: 10.1007/BF02906493.
The photosystem I mutant of barley, viridis-zb63, which totally lacks the P700-chlorophyll a-protein 1 was characterised by rotary shadowed, freeze-fracture electron microscopy. Objective measurements were made of particle density and size distribution for all four fracture faces, and compared with values for wild-type. A highly significant reduction in the size of the PFu particles was found, which could be attributed to the loss of a population of large particles from the mutant PFu face. A corresponding loss of EFu pits was also observed. It is concluded that the photosystem I reaction centre and two or three ancillary polypeptides are located in the large PFu particles which account for two-thirds of the total, and that these particles span the membrane. Since no differences were seen on the PFs and EFs faces, there was no evidence for the localisation of any photosystem I in appressed granal membranes, supporting the concept of extreme lateral heterogeneity. A model is presented of the localisation of different functional polypeptide units to different freeze-fracture particles within the membrane. A peculiar feature of viridis-zb63 thylakoids was the presence of EFs particle arrays in vivo.
大麦的光系统I突变体viridis-zb63完全缺乏P700-叶绿素a蛋白1，通过旋转阴影、冷冻断裂电子显微镜对其进行了表征。对所有四个断裂面的颗粒密度和大小分布进行了客观测量，并与野生型的值进行了比较。发现PFu颗粒的大小显著减小，这可能归因于突变体PFu面上大量大颗粒的丢失。还观察到相应的EFu凹坑的丢失。得出的结论是，光系统I反应中心和两到三个辅助多肽位于占总数三分之二的大PFu颗粒中，并且这些颗粒跨越膜。由于在PFs和EFs面上未观察到差异，没有证据表明任何光系统I定位于紧密堆积的基粒膜中，这支持了极端侧向异质性的概念。提出了一个模型，说明不同功能多肽单元在膜内不同冷冻断裂颗粒中的定位。viridis-zb63类囊体的一个独特特征是体内存在EFs颗粒阵列。
