Why does a "cascade" of events happen during signal transduction?

Question

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't understand why?Thanks.

Answer 1

Enzyme are biologic catalysts and as such affect the rate of reaction in which they are involved. If an enzyme is activated (or inhibited), the result is an effect on the rate of the catalyzed reaction. This then leads to "downstream" effects, which is referred to as a "cascade" of effects. For example, if a kinase is activated by a signal, this then results in increased phosphorylation of the appropriate substrate. Phosphorylation of the substrate then changes the chemical structure of this substrate, and hence can affect how it interacts with other moieties. It could have an inhibitory or a stimulatory effect. And then this interaction has effects on other "downstream" reactions.

Answer 2

Hi, lets walk through what goes on in a signal transduction!

In a signal transduction, the ligand (any molecule that will eventually attach to another molecule) is able to either bind onto a cell receptor (any ligand that is not a lipid) or is able to pass through the cell membrane (any ligand that is a lipid, such as a steroid). If the ligand passes through the cell membrane, it will attach to an enzyme. In either case, a signal transduction is produced. The cascade of events you want to understand, is what happens after the ligand attaches to the receptor. The cascade of events is critical to transmitting and amplifying the signal of the ligand into some cellular response. A great example of a cascade is the phosphorylation cascade. This occurs when the receptor that is attached to the ligand phosphorylates (or activates) a kinase. This kinase would then use its energy to phosphorylate another kinase. Then that kinase would use its energy to phosphorylate (or activate) a protein. This protein could in turn phosphorylate numerous other kinase molecules resulting in the amplification of the signal. Eventually the kinase will activate a certain protein that will create the desired cellular response.

If you would like to know more, just notify me and I can go more in depth.

I hope this makes sense!

Manu M.

Answer 3

The primary benefit to a cell when a signal transduction mechanism is triggered is amplification of signal. In theory, as little as one single extracellular receptor ligand can activate a whole-cell response. The ligand binds to its cell surface receptor, which activates the receptor's coupled GTP-binding protein on the intracellular side of the plasma membrane, which then activates a nearby membrane-bound enzyme such as adenylyl cyclase, which catalyzes the synthesis of many molecules of a second messenger like cyclic AMP, each of which activate intracellular protein kinase A molecules that add phosphate groups to their respective targets. Phosphorylation of proteins is a widespread mechanism for function activation, although in some cases, phosphorylation is inhibitory. The generation of the second messenger during the transduction process greatly amplifies the strength of a signal, thereby facilitating a whole-cell response to a vanishingly small amount of extracellular signal. The word "cascade" is used to convey the observation that the signal transduction process, once initiated, tends to execute to completion. There is little stopping it once it begins, just like how water in a waterfall finds its way to the bottom no matter what stands in its way.