cell cycle regulation

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MAP kinase cascade in the signal transduction pathway : Map kinase has been identified as a kinase which induce phosphorylation to activate maturation prompting factor (MAF) consisting of cdc2 and cyclin B.Drs.Nishida (Kyoto U.) and Sakata (Kyushu U.) clarified that Mos is a key regulator in the MAP kinase cascade.Identification of Licensing factor for DNA replication in S phase : In eukaryote, it is very important that the total genomic DNA is replicated only once in the S phase. To do that it has been assumed that cells possess a factor to license only the signal round of DNA replication in S phase. In this research program, Dr.Takisawa identified the protein factor which allow a single round of DNA replication. It is turned out to be a mammalian homologue of S.cereviae Mcm families.Cyclins in the cell cycle : Cyclins comprise either MPF or SPF with cdc2 or cdks that are so called cell cycle engines. In this context, it is a very important question why cyclins are essential for MPF a … More nd SPF functions. Drs Kobayashi (Kyushu U.) and Kishimoto (Tokyou Engineering U.) investigated the interaction between cdc2 and cyclin B during G2/M transition.Ubiqutin system in the cell cycle : Degradation of proteins depend on either ubiqutin or nonubiqutin cycle.in the cell cycle, the ubiqutin dependent protein degradation is important for the progression of cell cycle. It plays a impartant role for the regulation of cell cycle progression either. Dr.Tanaka (Tokushima U.) has identified proteins comprising the ubiqutin dependent proteasome and cloned the cDNA encoding these proteins.G protesin in the cell cycle : A small G protein functions as a biological switch. Thus far, many G proteins have been found to be involved in the signal transduction and the protein secretion. RCC1 which was cloned by the group of Dr.Nishimoto (Kyushu U.) functions as a GTP/GDP exchanging factor for a small nuclear GTPase Ran.Since loss of RCC1 induces premature initiation of mitosis, RCC1 is assumed to be involved in the cell cycle regulation Less