Question

Are hormones always proteins?

Answer 1

Hormones are called chemical messengers, which are secreted directly into the blood. They are carried by the blood to various organs and tissues to perform their respective functions. Hormones are secreted directly from the ductless endocrine glands. Major endocrine glands include the pineal gland, pituitary gland, thymus, thyroid, ovaries, testis, pancreas, and adrenal glands.

Complete answer
Not all hormones are proteins. There are 4 classes of hormones in humans.
1. First is amino acid derivatives – Examples are thyroxine, melatonin and neurotransmitters in brain and nerve cells.
2. Second is protein derivatives – Examples are Insulin, vasopressin, and thyrotropin-releasing hormone for small peptide hormones and thyroid-stimulating hormone, luteinizing hormones, and follicle stimulating hormones for glycoprotein hormones.
3. The third class is fatty acid derivatives or eicosanoids – They are signaling molecules, which are involved in allergic reactions, immune reactions, regulation of growth, and pain perception. An example is prostaglandins.
4. Fourth are cholesterol derivatives or steroid hormones – Examples are cortisol, estrogen, progesterone, dehydroepiandrosterone, and testosterone.
Protein hormones and peptide hormones are synthesized from mRNA inside the cell nucleus like any other protein. Prohormones are usually processed in the endoplasmic reticulum for the removal of the N-terminus and signal sequence. Sometimes, the addition of glycans is performed leading to glycosylation. This type of hormone is secreted by the cell in response to stimuli. Angiotensin, glucagon, and insulin are some well-known protein or peptide hormones.
Peptide hormones are short chains of linked amino acids and protein hormones are longer chains of linked amino acids. In amino acid derivatives, hormones are derived from single amino acid. But in peptide and protein derivatives, hormones are derived from multiple amino acids, which link to form a chain.

Note:
Hormones perform various bodily processes and functions. They aid in the development of growth and development. They carry out the metabolism of foods. They are responsible for sexual function, reproductive growth, and health. They help in establishing cognitive mood and function. They help in maintaining the body temperature and thirst. Hormone deficiency causes several diseases like acromegaly and graves’disease.