Function and Sorting Mechanism of Membrane ATPases
Grant-in-Aid for Scientific Research (B).
|Allocation Type||Single-year Grants|
|Research Institution||KYOTO UNIVERSITY|
TAKEYASU Kunio Kyoto Univ., Grad. School Biostudies, Professor, 大学院・生命科学研究科, 教授 (40135695)
竹安 邦夫 京都大学, 大学院・生命科学研究科, 教授 (40135695)
KRISHNA Sanj ロンドン大学, 聖ジョージ病院医学部, 准教授
MEAD John C. ミシシッピー大学, 医学部, 准教授
BAUMANN Otto ポツダム大学, 理学部, 准教授
FAMOROUGH Do ジョンスホプキンス大学, 芸術科学部, 教授
佐藤 雅彦 京都大学, 総合人間学部, 教授 (20283575)
|Project Period (FY)
1998 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1999 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1998 : ¥1,300,000 (Direct Cost : ¥1,300,000)
|Keywords||Na+ / K+-ATPase / Ouabain / Molecular Evolution / Subunit Assembly / Drosophila / Malaria / Nematoda(C. elegans) / 進化(分子進化) / テトラヒメナ / 膜ATPase|
The goal of this study is to identify and characterize every possible P-type ATPase in invertebrates.
(1) In collaboration with Dr. Baumann, we investigated the NaィイD1+ィエD1/KィイD1+ィエD1-ATPase in Drosophila photoreceptors which are highly polarized Immunofluorsecence and immunogold labeling of adult compound eyes reveal that the distribution of NaィイD1+ィエD1/kィイD1+ィエD1-ATPase is concentrated at the peripheral surface in photoreceptors R1-R6, but extends over the juxtarhabdomeric domain to the rhabdomere in the photoreceptors R7/R8. Developmental analysis demonstrates further that NaィイD1+ィエD1/KィイD1+ィエD1-ATPase is localized over the entire plasma membrane in all photoreceptors in early pupal eyes. Redistribution of NaィイD1+ィエD1/KィイD1+ィエD1-ATPase in R1-R6 occurs at about 78% of pupal life, coinciding with the onset of Rh1-rhodopsin expression on the central of these cells. This leads to the differential distribution of NaィイD1+ィエD1/KィイD1+ィエD1-ATPase and rhodopsin, which is maintained independent
of each other.
(2) We developed a complete list of the P-type ATPase genes in Caenorhabditis elegans and Drosophila melanogaster. A detailed comparison of the deduced amino acid sequences in combination with phylogenetic and chromosomal analyses has revealed the followings : (1) The diversity of this gene family has been achieved by two evolutionary steps; the establishment of the subgroups with distinct substrate (ion) specificities in a common ancestor of vertebrate and invertebrate, and the following isoform separation within a single subgroup that occurred independently in vertebrate and invertebrate. (2) Two genes that have intimate phylogenetic relationship are frequently found as cluster on the same chromosome.
(3) The NaィイD1+ィエD1/KィイD1+ィエD1-and the HィイD1+ィエD1/KィイD1+ィエD1-ATPases, members of the P-type ATPase, are usually composed of α and β subunits, but some of the isoforms in D. melanogaster and C. elegans lack the assembly domains, suggesting that such α and β subunits would exist by themselves (lonely subunits). The rates of evolution for these subunits are much faster then those for the subunits that assembles normally. The lonely α subunits also lack the major sites for the inhibitors such as ouabain and SCH28080, and represent a primitive type of NaィイD1+ィエD1/KィイD1+ィエD1-(HィイD1+ィエD1/KィイD1+ィエD1) ATPase that appeared before the separation of vertebrates and invertebrates and also before the establishment of NaィイD1+ィエD1/- and HィイD1+ィエD1-ATPases. these findings support the idea that a relaxation of functional constraints (e.g., removal of the requirement for subunit assembly) would increase the rate of evolution, and provide the clues for identifying the origins of inhibitor sensitivity, subunit assembly, and separation of NaィイD1+ィエD1/KィイD1+ィエD1- and HィイD1+ィエD1/KィイD1+ィエD1-ATPases.
(4) In collaboration with Dr. Krishna, we found a wide variety of P-type ATPases in in Malaria parasite, Plasmodium falciparum. An analysis of the evolutionary relationships between 7 P. falciparum P-type ATPases identified no functionally characterized example of a NaィイD1+ィエD1/KィイD1+ィエD1-ATPase. Less
Research Output (11results)