Tonoplast membrane

HOGLUND A.-S., LENMAN, M., RASK, L., Myrosinase is localized to the interior of myrosin grains and is not associated to the surrounding tonoplast membrane., Plant... 

The vacuole, enclosed by the tonoplast membrane, may constitute as much as 90% of the volume of the mature plant cell and can provide a temporary storage site for intermediary metabolites such as organic acids. Substances such as tannins and calcium oxalate appear to be permanently deposited in the vacuole. It also seems to serve as a repository for metabohtes that could be toxic to the plant cell. It has been demonstrated that the glutathione conjugate of metolachlor, a herbicide... 

Fig. 1. Proposed process by which an infection thread passes through a cell wall between two plant cells, in this case between the root hair cell and an adjacent cortical cell. (1) The membrane at the tip of the infection thread has fused with the root hair cell plasma membrane to form a pore. Tonoplast membrane, TM infection thread membrane ITM rhizobia, R infection thread wall, ITW root hair cell cytoplasm, RHCC root hair cell plasma membrane, RHCP plant cell wall, PCW cortex cell plasma membrane, CCP cortex cell cytoplasm, CCC. The arrows and vesicles represent intense activity of the endomembrane system involved in the synthesis of membranes and wall material. (2) The rhizobia have forced their way, by dividing, into the region between the two cells although they are still enclosed by wall material. (3) An intercellular infection thread is formed by degradation and resyntheses of cell wall material in the vicinity of the dividing rhizobia. (4) The infection thread has entered the cortical cell by promoting invagination and growth of the plasma membrane and wall of that cell, in front of the dividing bacteria.

A bottom layer consisting mainly of lutoid particles and also including other particulate components with a density greater than that of serum. Lutoid particles amount to 15 to 20% of latex volume. Their negatively charged tonoplast membrane, rich in phosphatidic acid, encloses a fluid serum known as B-serum. The vacuolar medium is acidic and positively charged. It includes cations, basic amino acids and a whole... 

In fungal cells (Neurospora, yeasts) the expandable pool was shown to be localized in vacuoles which can be isolated (4, 10) and contain their own specific transport system in the tonoplast membranes (10 Thus vacuoles are main storage sites of amino acids of fungal (and plant ) cells. Further, they may function as dominant regulatory agents, if uptake and release are responsive to changes in cytosolic pool sizes (5). 

A wound response also seems implicated in the stimulation by ethephon of latex flow during tapping of rubber trees, a response which has been shown to be associated with a change in the trans-tonoplast membrane potential [13]. The increased production of secondary metabolites such as latex is probably a common... 

The higher levels of GS II activity and the higher proportions of sterols, VLCFA, and saturated fatty acids in the upper phase are in agreement with the purification of the plasma membrane. The low CDP-choline diglyceride transferase activity in the upper phase indicates the very low contamination by membrane vesicles originating from the endoplasmic reticulum. Lastly, other analyses have suggested that this purified plasma membrane fraction is only slightly contaminated by plastidial, mitochondrial, and tonoplastic membranes. ... 

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