One of the most integral building blocks of life is the transport protein. These proteins can be found in the membranes of cells and their subcellular organelles, and are responsible for facilitating some of the most essential physiological processes. All of the information regarding transport proteins in this overview was found in Molecular Cell Biology 3rd Ed. by Lodish et al. (1995).

Some of the processes transport membranes enable cells to carry out include maintaining cytosolic pH, transporting glucose across the intestinal epithelium, the accumulation of sucrose and salts in plant-cell vacuoles and the directed flow of water in both plants and animals. Transport proteins in differing combinations can allow for a wide variety functions, so each type of transport protein can be used for very different purposes.

There are three major types of transport proteins that are found in membranes, ATP powered pumps, channel proteins, and transporters. ATP powered pumps are ATPases. They use ATP hydrolysis to move ions across a membrane against their concentration gradient. Channel proteins open for ions to cross the membrane down their concentration gradient, and can be gated.

In this article, the researchers inhibited the transporting activity of the tonoplast in barley vacuoles. They were observing how and what would prevent the uptake of glutathione and another transporter involved in detoxification, taurocholate. Judging by the kinetic properties of the transporters, they concluded that the are two ATP-dependant amphiphilic anion transporters present in the vacuole. They also saw that by looking at the types of compounds that provoked inhibition of the transporter, that generally each transporter type preferred a certain specific type of substrate, but there was some overlap. This is also where they saw similarities with some mammalian transporters, particularly in multidrug resistance (Mechteld et al.,1996).

Cole et al.(1995). Overexpression of a Transporter Gene in a Multidrug-Resistant Human Lung Cancer

Lodish et al (1995). Molecular Biology 3rd Ed. Scientific American Books. Pp634-659

The paper by Mechteld et al, could have an impact on the production of genetically modified plants, in that it is beginning to shed some light on a plants ability to cope with stresses from the world around it. With the increasing amounts of pollutants in the air and water, if research finds ways to use the framework that is already in place and manipulate the natural defense systems of vegetation, to provide the world with heal

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