Describe how protein kinases and protein linked receptors may interact in a signal transduction cascade?

Question

Describe how protein kinases and protein linked receptors may interact in a signal transduction cascade?

Answer 1

In a signal transduction cascade, you have the first messenger or ligand, which interacts with a receptor. The receptor then changes confirmation and induces a change in some other molecule or membrane which then results in activating or inhibiting some other molecule, the second messenger. In the case of a protein kinase, this second messenger then activates or inhibits the protein kinase which is responsible for phosphorylating some other protein in the cell. The phosphorylation of this other cellular protein affects how it functions. Sometimes phosphorylation of the protein activates it and sometimes it inhibits it. Either way, the biologic response is affected. This, in essence, is the "cascade" of signal transduction. In summary, you have the following:

1. signal (first messenger) binds to receptor.
2. receptor changes shape and affects some cellular component (the second messenger)
3. the second messenger (cAMP for example) activates protein kinase
4. the activated protein kinase phosphorylates a target protein
5. this target protein is either activated or inhibited by such phosphorylation
6. some cellular process is affected