Immunoelectron microscopic studies on the behavior of photosynthetic protein in Euglena

点击翻译按钮获取中文摘要

The precursors to the Euglena light-harvesting chlorophyll a/b binding proteins of photosystem II (LHCP II) are large polyproteins containing multiple copies of LHCP II covalently joined by a conserved decapeptide. Light induced LHCP II synthesis is controlled at the translational level in Euglena rather than the transcriptional level as found in higher plants and other algae. Under conditions promoting LHCP II synthesis and accumulation in the thylakoids, a reaction with anti-LHCP II antibody can be observed by immunogold electron microscopy in the Golgi apparatus. The kinetics of LHCPII appearance in the Golgi apparatus as measured by immunogold electron microscopy in synchronous cells and by pulse labeled with H_2[^<35>S]O_4 in cells undergoing normal light-induced chloroplast development suggests that nascent LHCP II is transported to the Golgi apparatus prior to chloroplast import and thylakoid insertion.The few views of the compartmentalized osmiophilic body (COS) that we have obtained indicate the presence of LHCP II apoprotein. It is not possible to provide systematic data for this structure throughout the cell cycle since it is small and difficult to find. Further experiments are required to clarify the nature of the COS and its role in LHCP II synthesis.