Poster: Comparative Genomics

Abs # 916: Comparative molecular biological analysis of plant calcium signal transduction genes from full-length cDNA data

Presenter:	Toshifumi, Nagata , nagatat@nias.affrc.go.jp
Authors	Toshifumi, Nagata  (A)   Kouji, Sato  (A)   Hisako, Ooka  (B)   Jun, Kawai  (C)   Piero, Carninci  (C)   Yasuhide, Hayashizaki  (C)   Yasuhiro, Ohtomo  (D)   Kazuo, Murakami  (D)   Kenichiro, Matsubara  (D)   Shoshi, Kikuchi  (A)
Affiliations:	(A): National Institute of Agrobiological Sciences (B): Nagaoka Univercity of Sciencetechnology (C): RIKEN Institute (D): Foundation for Advancement of International Science

We obtained 28K full-length cDNA sequence data from the rice full-length cDNA project and performed a homology search against NCBI GenBank data. Comparative analysis of calcium ion transporter proteins revealed that the cell-to-cell calcium signal transduction systems (e.g., voltage-dependent calcium channel (VDCC), IP3 receptor, ryanodine receptor) are very different in animals and plants. In contrast, signal transduction systems inside individual cells (e.g., cyclic nucleotide-gated channel (CNGC), Ca²⁺ATPase, Ca²⁺H⁺ ion exchanger, Ca²⁺Na⁺ion exchanger, Glu receptor) are well conserved between plants and animals. This difference may have evolved in animals because of the need to develop rapid and multiple cell-to-cell signal transduction systems in muscles and nerves. We also performed comparative analyses of calcium-binding proteins in both organisms, including Ca²⁺ion binding EF-proteins (e.g. calmodulin, caltractin, calcineulinB, centrin, fimbrin, calmenin, calpain, sorcin). Ca²⁺ion/phospholipid-binding protein (phospholipase C, annexin) and calcium storage protein (calreticulin) were common to both plants and animals. Many genes specific for muscle- and nerve-tissue-specific EF-hand proteins, ƒÁ-glutamic-acid-containing proteins, and phosphoric acid binding proteins are not exist in plants. However, plants have developed a calcium ion interacting system that is more direct than in animals. There are many species of plants with specifically modified calcium ion binding proteins (CPK, CRK), Ca²⁺/phospholipid binding domains, and calcium storage proteins. Plant systems have evolved to simplify the signal cascade by skipping the transduction step by the use of CDPK and CRK.