A large number of proteins in the vacuolar membrane (tonoplast), including pumps, carriers, ion channels and receptors support the various activities of the plant vacuole. Molecular analysis of these proteins is an essential step in understanding how vacuoles function. However, few proteins involved in these activities have been identified at the molecular level. In part this is due to the difficulty in detecting the low levels of protein activity in the vacuolar membrane, and in part due to the relative lack of mutants related to physiological functions of the vacuole. Proteomic analysis of Arabidopsis and barley has been used by several groups to try to identify new vacuolar membrane proteins. A primary requirement of any organelle analysis by proteomics is that the purity of the isolated organelle needs to be high so that its composition can be unambiguously analyzed by mass spectrometry. Proteins identified so far include previously well-characterized proteins such as V-type H+-ATPases and V-type Hf-PPases, along with a number of novel proteins. Functions of some of these newly identified proteins seem reasonable for their location in the membrane; for most others though, function has not been established. In this chapter, we examine recent advances in our understanding of vacuolar proteomics, focusing on important aspects of methodology and on newly identified proteins.
|Title of host publication
|Plant Membrane and Vacuolar Transporters
|Number of pages
|Published - 2008 May 14
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences(all)