The Vacuolar-ATPase of Paramecium multimicronucleatum: Gene Structure of the B Subunit and the Dynamics of the V-ATPase-rich Osmoregulatory Membranes
| Autor: | Richard D. Allen, Kiyoshi Yamauchi, Agnes K. Fok, Akinori Ishihara, Marilynn S. Aihara, Masaki Ishida |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Vacuolar Proton-Translocating ATPases
Paramecium Protein subunit Molecular Sequence Data Vacuole Biology Microbiology Animals V-ATPase Amino Acid Sequence Cloning Molecular Peptide sequence Gene Library Base Sequence Sequence Homology Amino Acid Vesicle Sequence Analysis DNA Water-Electrolyte Balance biology.organism_classification Contractile vacuole Molecular Weight Blotting Southern Microscopy Electron Cytosol Microscopy Fluorescence Biochemistry Vacuoles Biophysics |
| Zdroj: | The Journal of Eukaryotic Microbiology. 49:185-196 |
| ISSN: | 1550-7408 1066-5234 |
| DOI: | 10.1111/j.1550-7408.2002.tb00521.x |
| Popis: | Previous studies have shown that the vacuolar-ATPase (V-ATPase) of the contractile vacuole complexes (CVCs) in Paramecium multimicronucleatum is necessary for fluid segregation and osmoregulation. In the current study, immunofluorescence showed that the development of a new CVC begins with the formation of a new pore around which the collecting canals form. The decorated membranes are then deposited around the newly formed collecting canals. Quick-freeze deep-etch techniques reveal that six 10-nm-wide V-ATPase V, sectors, tightly packed into a 20 x 30-nm rectangle, form two rows of these compacted sectors that helically wrap around the cytosolic side of decorated membrane tubules. During new CVC formation, packing of decorated tubules around mature CVCs was temporarily disrupted so that some of these decorated tubules became transformed into decorated vesicles. Freeze-fracturing of these decorated vesicles revealed a highly pitted E-face and a particulate P-face. The V-ATPase was purified for the first time in any ciliated protozoan and shown to contain, as in other cells, the V1 subunits A to E, and four 14-20 kDa polypeptides. The B subunit was cloned and found to be encoded by one gene containing four short introns. This subunit has 510 amino acid residues with a predicted molecular weight of 56.8 kDa, a value similar to B subunits of other organisms. Except for the N- and C-termini, it has a 75% sequence identity with other B subunits, suggesting that the B subunits in Paramecium, like other species, have been conserved and that the entire surface of this subunit may be important in interacting with other subunits. |
| Databáze: | OpenAIRE |
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