Abstract
Plant cells highly develop complicated and sophisticated endomembrane systems including endoplasmic reticulum (ER), Golgi complex and vacuole. However, little is known how such structures of endomembrane systems are organized in the plant cells. Recently, we generated a transgenic Arabidopsis plants expressing a vacuole-targeted GFP to visualize the endomembrane systems. We mutagenized this transgenic Arabidopsis plants and screened for mutants, which exhibited abnormal structures of endomembrane systems. We isolated a mutant, katamari1, in which endomembrane formed an aggregation. Fluorescent markers and ultrastructural analysis showed that most of ER, Golgi, endosomes, peroxisomes and vacuoles were aggregated in the mutant cells. Interestingly, some of actin filaments were also aggregated. Positional cloning revealed KATAMARI1 gene encoding a type II membrane protein. We will discuss a function of the KATAMARI1 protein responsible for a proper organization of endomembrane.
