Contractile Vacuole Complex—Its Expanding Protein Inventory - International Review of Cell and Molecular Biology - page 365

CHAPTER NINE

Contractile Vacuole Complex

—
Its Expanding Protein Inventory

Helmut Plattner 1
Department of Biology, University of Konstanz, Konstanz, Germany
1 Corresponding author: e-mail address: [e-mail]

Contents
1. Introduction 372
2. Basic Structural and Functional Elements of CVC 372
2.1 Basic structure of CVC 373
2.2 Proton pump as a basic constituent 375
2.3 Proteins required for membrane trafficking 376
3. Handling of Calcium by CVC 383
3.1 Calcium uptake by CVC 383
3.2 Ca 2þ release from the CVC by Ca 2þ -channels 385
4. Unique Structural Aspects and Molecular Components 390
4.1 What enables reversible organelle expansion and collapse? 390
4.2 CVC components known specifically from Dictyostelium 391
5. Cytoskeletal Elements, Motor Proteins, Endocytotic Input, and Clathrin 393
5.1 Cytoskeletal components and motor proteins 393
5.2 Endocytotic input and role of clathrin 395
6. The CV Pore and Epigenetic Aspects of Organelle Positioning 396
6.1 Components of the CV pore 396
6.2 Biogenesis and epigenetically determined positioning of CVC in Paramecium 398
7. Conclusions and Hypotheses 400

7.1 Summary of a molecular anatomy of CVC 400

7.2 Generalized scheme of CVC function 401

7.3 Steady-state biogenesis by vesicle trafficking and protein turnover 402

7.4 Hypothetic considerations about de novo CVC biogenesis 404

7.5 Complexity of protein pattern to be expected in future research 406

Acknowledgment 407

References 407

Abstract
The contractile vacuole complex (CVC) of some protists serves for the osmotic equili-
bration of water and ions, notably Ca 2þ , by chemiosmotic exploitation of a H þ gradient
generated by the organelle-resident V-type H þ -ATPase. Ca 2þ is mostly extruded, but
there is also some reflux into the cytosol via Ca 2þ -release channels. Most data available