Biomedical Engineering Reference
In-Depth Information
Fig. 7.3
Signal transduction pathways and transcriptional (nuclear) actions of protein and peptide
hormones
Chemical Structures of the Three
Major Classes of Human Hormones
Hormones are derived from amino acids, from cholesterol, or from phospholipids
[
1
-
4
]. By far the most numerous are the
protein or peptide hormones
, ranging in
size from just 3 to over 200 amino acids. Some hormones, such as insulin, are made
up of two sub-units joined by disulfi de bonds between two cysteine molecules
whilst the glycoprotein hormones of the anterior pituitary gland are not only made
up of two protein sub-units but also have complex sugar moieties attached. Other
hormones include those derived from tryptophan (serotonin and melatonin) and
those derived from fatty acids (eicosanoids).
