Do you know that plants also benefits from steroids the way humans do? Just like in athletes, plants bulk up when injected with steroids. But their molecular signals, which give instructions to boost development and growth in plant cells, are much more complicated than how it is in animals and human cells.

Plant biologists at the Carnegie Institution used proteomics, a molecular approach that identifies key links in the signaling chain of steroids. With this method, new insights into how steroids are able to regulate growth and development in plant cells as well as in animal cells can be made by understanding how the plant hormones activate genes.

The study, led by Wenqinag Tang and Zhi-Yong Wang, looked at brassinosteroids, plant steroids that are the key hormones in the plant kingdom. Brassinosteroids play a major role in regulating many aspects of plant growth and development. Mutant plants that are deficient in this hormone are infertile and exceedingly stunted. This plant hormone also shares many similarities with animal steroids but appear to have very different functions in the cellular level. In animal cells, steroids use internal receptor molecules to get a response within the cell’s nucleus. In plant cells, the receptors are anchored to the cell membranes’ outside surface.

The researchers had to piece the steps together of how hormone signal is transmitted to the surface receptor of the cell to its action in the cell’s nucleus whenever the regulation has the genes for its target. Various components of the BR signaling pathway have been identified in the use of traditional genetic methods. However, this traditional approach cannot identify all signaling pathway components mainly because many genes play the same role in one cell—what is called genetic redundancy, makes identification a lot harder.

To make identification easier, the researchers used proteomics techniques to spot the links in the chain of signal transduction. Wang says that proteomics is similar to genomics because in genomics, what is aimed for is a complete survey of all genes in the genome while in proteomics, what is aimed for is a complete mapping of the proteins.

A single organism constitutes of thousands of different proteins; thus, proteomics require processes that can segregate thousand for proteins at a time. Techniques such as 2-dimensional gel electrophoresis can process thousands of proteins according to size and charge.

Still, even with this technique, it can be difficult to isolate the proteins’ low-abundance signaling. The more abundant proteins swamped the molecules to be identified, making earlier attempts unsuccessful. What the researchers did was separate the membranes from the cell material and analyzed the fraction since they knew that proteins would be associated with the cell membrane. They targeted a particular class of proteins that exchanged phosphate ions to transmit signals and which were known as kinases.

The presence of brassinosteroids was detected by identifying a group of kinases that responded to it, using electrophoresis. The researchers called these proteins brassinosteroid signaling kinases or BSKs. Wang’s study will offer a new paradigm for how hormones work as well as have a major impact on future studies of signal transduction pathways.

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