Molecules such as cAMP or Inositol trisphosphate are used in organisms as messenger molecules that make things happen when they are supposed to happen. These molecules are usually big, but not too big, are usually charged, and most have a noticeable 'shape'. My question is what kind of generalizations you can draw about the size, charge, and shape of messenger molecules (when talking specifically about the human body).

All I've really been able to conclude using arguments that make sense to me is that messenger molecules are usually charged because changes in charge are the fastest means of communication in biological systems and charged particles react best to changes to a charge gradient.

My questions are:

  1. Why aren't messenger molecules made up of as few particles as can be mustered into a functioning molecule? Would that not make the molecule lighter, faster, and therefore better because it is able to respond quickly?
  2. Is there any general 'shape' or composition of messenger molecules like cAMP that I am missing? What purpose does this shape serve?
  3. Is my argument on why messenger molecules usually have charge valid? Is there any other important function/trait of the charge of messenger atoms that I am missing?

Most of my questions are what I have drawn from my notes; I may be wrong. I would appreciate a kind indicator toward where I may have a misunderstanding.

  • 1
    $\begingroup$ Thoughtful question. I'm not sure it makes a good SE question (multiple parts, more of a discussion question, some parts are opinion based), but along that line consider the properties of calcium and its role as a second messenger. How does that impact your thoughts about second messenger systems? $\endgroup$ – De Novo Oct 14 '18 at 2:26
  • $\begingroup$ Very nice reasoning indeed. As indicator(s) for further thoughts on point 3): How do sterols differ from other messengers? Why do protein-phosphorylations tend to occur within sterically flexible, unstructured, parts or a protein? $\endgroup$ – tsttst Oct 15 '18 at 6:13

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