Editing Endorphins (section)

== Types ==
{{expand section|date=December 2018}}
The class of endorphins consists of three [[Opioid peptide#Endogenous opioids|endogenous opioid]] peptides: [[α-endorphin]], [[β-endorphin]], and [[γ-endorphin]].<ref name="Endogenous opioid families - 2012 review">{{cite journal | vauthors = Li Y, Lefever MR, Muthu D, Bidlack JM, Bilsky EJ, Polt R | title = Opioid glycopeptide analgesics derived from endogenous enkephalins and endorphins | journal = Future Medicinal Chemistry | volume = 4 | issue = 2 | pages = 205–226 | date = February 2012 | pmid = 22300099 | pmc = 3306179 | doi = 10.4155/fmc.11.195 }}</ref>  The endorphins are all synthesized from the precursor protein, [[proopiomelanocortin]], and all contain a Met-enkephalin motif at their N-terminus: Tyr-Gly-Gly-Phe-Met.<ref name="Purves2018" /> α-endorphin and γ-endorphin result from proteolytic cleavage of β-endorphin between the Thr(16)-Leu(17) residues and Leu(17)-Phe(18) respectively.<ref name=":562">{{cite journal | vauthors = Burbach JP | title = Action of proteolytic enzymes on lipotropins and endorphins: biosynthesis, biotransformation and fate | journal = Pharmacology & Therapeutics | volume = 24 | issue = 3 | pages = 321–354 | date = January 1984 | pmid = 6087385 | doi = 10.1016/0163-7258(84)90008-1 | hdl-access = free | hdl = 1874/25178 }}</ref> α-endorphin has the shortest sequence, and β-endorphin has the longest sequence.

α-endorphin and γ-endorphin are primarily found in the anterior and intermediate pituitary.<ref name=":8">{{cite book |doi=10.1016/S0079-6123(08)64588-4 |chapter=Chapter 29 Endorphins and schizophrenia |title=The Human Hypothalamus in Health and Disease, Proceedings of the 17th International Summer School of Brain Research, held at the Auditorium of the University of Amsterdam |series=Progress in Brain Research |date=1992 |volume=93 |pages=433–453 |isbn=978-0-444-89538-7 | vauthors = Wiegant VM, Ronken E, Kovács G, De Wied D }}</ref> While β-endorphin is studied for its opioid activity, α-endorphin and γ-endorphin both lack affinity for opiate receptors and thus do not affect the body in the same way that β-endorphin does. Some studies have characterized α-endorphin activity as similar to that of psychostimulants and γ-endorphin activity to that of neuroleptics separately.<ref name=":8" />

{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
|-
! Name
! Sequence
! Reference
|-
| [[α-endorphin]]
| Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-OH
| <ref name=":0">{{cite journal | vauthors = Ling N, Burgus R, Guillemin R | title = Isolation, primary structure, and synthesis of alpha-endorphin and gamma-endorphin, two peptides of hypothalamic-hypophysial origin with morphinomimetic activity | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 73 | issue = 11 | pages = 3942–3946 | date = November 1976 | pmid = 1069261 | pmc = 431275 | doi = 10.1073/pnas.73.11.3942 | doi-access = free | bibcode = 1976PNAS...73.3942L }}</ref><ref name="Purves2018" />
|-
| [[β-endorphin]]
| Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu-Phe-Lys-Asn-Ala-Ile-Ile-Lys-Asn-Ala-Tyr-Lys-Lys-Gly-Glu
| <ref name=":4">{{cite book |last1=Chaudhry |first1=Shazia R. |last2=Gossman |first2=William |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK470306/ |chapter=Biochemistry, Endorphin  |pmid=29262177 }}</ref><ref name=":1" />
|-
| [[γ-endorphin]]
| Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu-OH
| <ref name=":0"/><ref name="Purves2018" />
|}