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Proteohormones and peptide hormones are lipid-insoluble / lipophobic (= fat-insoluble) hormones that have a protein structure ( protein = protein), that is, they consist of linked amino acids and are produced by protein biosynthesis . It is therefore special proteins that perform hormonal functions, i.e. messenger functions, which effect certain regulations in animal, including human bodies. Most of the types of hormones are proteohormones.

There are native and synthetic proteohormones, which means that they are produced naturally in the body, but they can also be produced and administered artificially. Proteohormones are used in human and veterinary medicine to influence various functions of organisms.


Like steroid hormones, proteohormones are a group of biomolecules . The term proteohormone refers to the structural classification of hormones. Proteohormones are protein molecules and therefore differ structurally from the ring molecules with steroid structure (see steroid hormones , steroids), the eicosanoids and the biogenic amines (catecholamines such as adrenaline).

Chemically classified, the proteohormones can also be differentiated from the amino acid derivatives, isoprene derivatives, steroid hormones and the fatty acid derivatives.

Peptide hormones

Peptide hormones are proteohormones, but consist of fewer amino acids and, from a chemical point of view, are peptides : amino acids linked by peptide bonds .

Peptides are short-chain proteins. If fewer than 10 amino acids are linked in a chain, one speaks of oligopeptides . If 10 to 100 amino acids are chained together, one speaks of polypeptides . If more than 100 amino acids are chained together, it is called a protein. However, polypeptides are also proteins, but should also be understood as a generic term. In the nomenclature of peptides and proteins, there is a contradiction in terms of the number of amino acids for some molecules. Amino acid chains that do not have more than 100 amino acids are considered peptides. A peptide hormone is understood to be a messenger substance (hormone) which, from a chemical point of view, is a peptide which is made up of several (3–191) amino acids and has hydrophilic properties. Peptide hormones, e.g. For example, interleukins have more than 100 amino acids, although according to the nomenclature they are considered small proteins or peptides. So one should carefully increase the limit of the amino acids in peptides to 200.

The peptide hormones can also be classified according to their molecular mass . Insulin and somatotropin , both hormones with a polypeptide structure , have a higher molar mass than, for example, ACTH , a peptide hormone with a lower molar mass.


Peptide hormones can be made up of one or more amino acid chains. For example, LH and FSH, unlike ACTH, consist of two peptide chains. The two chains are then referred to as the α and β subunits.


Like all proteins, the peptide hormones are also synthesized in vivo by means of protein biosynthesis.

Signaling pathways

Like other hormones, the proteohormones are secreted into the blood after their formation, where they can carry out their endocrine functions. Like all hormones , they are therefore extracellular signaling molecules, ie they are molecules that occur outside of cells. After their formation and secretion, they circulate in the blood, but are not fundamentally active. Proteohormones are even changed in the blood and thus regulated. The biological activity of the proteohormones depends u. a. from a sugar component (also called a carbohydrate component) that is attached to the protein structure. Active hormones can, after contact and interaction (interaction) with suitable cellular receptors, which can be located in cell membranes , in the cytosol or the nucleus of cells, develop their hormonal effect, transmit the signal and trigger actions in the cells. The hormone-receptor binding often triggers the formation of a signaling molecule in the cells.

Some of the hormones circulating in the blood are also removed from the blood. The sugar component attached to the protein is used for this purpose. If sialic acid is enzymatically split off from this sugar, the proteohormone can bind to the receptors of liver cells. The process is called endocytosis . This causes the hormone to disappear from the blood.


Inactive hormones can e.g. B. be detected by specific antibodies against the corresponding hormone, although they are no longer the original molecule.


Proteo and peptide hormones have also been on doping lists since 1989. Especially EPO (blood doping) , hCG (testosterone production in men) , hGH (growth) or ACTH are included in the lists.


Proteohormones have many different functions and tasks in organisms.


Short-chain peptides (oligopeptides)

  • Oxytocin (labor hormone, uterine contraction, 9 amino acids)
  • ADH (= vasopressin; 9 amino acids; regulation of the water balance)
  • Bradykinin (9 amino acids)
  • Desmopressin (synthetic, 9 amino acids)

Longer chain peptides

  • Gonadoliberin (10 amino acids) (decapeptide)
  • Insulin (A chain: 21 amino acids, B chain: 30 amino acids; regulation of the blood sugar level)
  • Glucagon (29 amino acids) (polypeptide)
  • Gastrin (big gastrin: 34 amino acids, gastrin I and II: 37 amino acids, mini gastrin: 14 amino acids)
  • Somatostatin (14 AS)
  • Calcitonin (32 amino acids) (Ca metabolism: Ca 2+ level reduction)
  • Obestatin (food regulation, appetite suppressant; 23 amino acids, precursor 117 amino acids)
  • Parathyroid hormone (84 amino acids) (Ca metabolism: Ca 2+ level increase)
  • ANF (33 amino acids) Natriuretic peptide
  • Ghrelin (28 amino acids) (food regulation, appetite-increasing)
  • HCG (Human Chorionic Gonadotropin) (α-subunit: 92 amino acids, β-subunit: 145 amino acids)


Glycoprotein hormones of the pituitary and hypothalamus : TSH thyrotropin (thyroid-stimulating hormone) (thyroid function)

  • TRH Thyreoliberin (releasing hormone)
  • FSH follitropin (follicle stimulating hormone) (follicle growth, sperm formation)
  • LH luteotropin (luteinizing hormone) (α-subunit: 92 amino acids, β-subunit: 118 amino acids)
  • ACTH adrenocorticotropin (adrenocorticotropic hormone) (39 amino acids)
  • MSH (melanocyte stimulating hormone)
  • EPO (Erythropoietin) (165 amino acids)

Growth hormones:

  • G-CSF (Granulocyte Colony Stimulating Factor, 174 amino acids)
  • IGF (insulin-like growth factor, insulin-like growth factors)
  • Somatotropin (= HGH = GH = STH) (191 amino acids)

Neuropeptides of the hypothalamus:


Individual evidence

  1. ^ DocCheck Medical Services GmbH: peptide hormone. Retrieved July 19, 2020 .