Many orphan sequences are being produced by human genome project. As the first step to the prediction of their structure and function, a software system SOSUI for discriminating membrane proteins from amino acid sequences alone was developed which is available on an internet web page. The analyses of amino acid sequence from total genomes by SOSUI system showed various interesting results, including the constant ratio (about 25%) of membrane proteins in total ORFs from bacteria to eukaryota. The physical background of the algorithm of SOSUI is discussed together with the results of the genome scale calculation.
Advances in microarray techniques have enabled us to simultaneously monitor the expression levels of thousands or tens of thousands of genes under multiple conditions. Here, we present a novel method to analyze a large amount of gene expression profiles by the combination of the standard statistical techniques. The method is composed of two parts : the automatic determination of cluster boundaries in a hierarchical clustering and the following inference of a network by application of graphical Gaussian modeling. The feasibility of our method is discussed in terms of the biological knowledge of gene regulatory systems and the other analytical approaches.
At the onset of mitosis, each organelle in a mammalian cell must be inherited accurately by two daughter cells. Recent advances in GFP visualization techniques and in genetic approaches have made it possible to understand the dynamic behavior of organelle during their inheritance and to identify the intracellular machinery required for accurate inheritance. Extensive studies have revealed that the inheritance strategies used by each organelle are not stochastic and passive but are rather controlled by the molecules, which are needed for membrane fusion/vesiculation in intracellular membrane traffics and for organelle architecture. Here we review current knowledge of organelle inheritance briefly and describe our recent findings, which have been obtained using our novel "semi-intact cell systems", with regard to the inheritance mechanisms of Golgi apparatus and endoplasmic reticulum in mammalian cells.