Editing Peripheral membrane protein (section)

==Categories==

===Enzymes===
Peripheral enzymes participate in [[metabolism]] of different membrane components, such as lipids ([[phospholipase]]s and [[cholesterol oxidase]]s), [[cell wall]] [[oligosaccharides]] ([[glycosyltransferase]] and [[transglycosidases]]), or proteins ([[signal peptidase]] and [[palmitoyl protein thioesterase]]s). [[Lipases]] can also digest lipids that form [[micelle]]s or nonpolar droplets in water.

{| class="wikitable" style="margin: 1em auto 1em auto"
!width="180"|Class
!width="275"|Function
!width="305"| Physiology
!width="50"| Structure
|-
| [[Alpha/beta hydrolase fold]] || Catalyzes the [[hydrolysis]] of chemical bonds.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00561 |title=Pfam entry Abhydrolase 1 |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929115310/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00561 |archive-date=2007-09-29 |url-status=dead }}</ref>|| Includes [[bacteria]]l, [[fungal]], gastric and pancreatic [[lipase]]s, palmitoyl protein [[thioesterase]]s, [[cutin]]ase, and [[cholinesterase]]s ||central beta sheet inserted in between two layers of alpha helices<ref>{{Cite journal |last1=Bauer |first1=Tabea L. |last2=Buchholz |first2=Patrick C. F. |last3=Pleiss |first3=Jürgen |date=March 2020 |title=The modular structure of α/β-hydrolases |journal=The FEBS Journal |language=en |volume=287 |issue=5 |pages=1035–1053 |doi=10.1111/febs.15071 |issn=1742-464X|doi-access=free |pmid=31545554 }}</ref>
|-
| [[Phospholipase A2]] (secretory and cytosolic) || Hydrolysis of sn-2 [[fatty acid]] bond of [[phospholipid]]s.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00068 |title=Pfam entry: Phospholipase A2 |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929110908/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00068 |archive-date=2007-09-29 |url-status=dead }}</ref>||Lipid digestion, membrane disruption, and [[lipid signaling]]. ||contains catalytic amino acid triad: [[aspartic acid]], [[serine]], and [[histidine]]<ref>{{Citation |last1=Casale |first1=Jarett |title=Biochemistry, Phospholipase A2 |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK534851/ |work=StatPearls |access-date=2023-11-29 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30521272 |last2=Kacimi |first2=Salah Eddine O. |last3=Varacallo |first3=Matthew}}</ref> 
|-
| [[Phospholipase C]] || Hydrolyzes PIP2, a [[phosphatidylinositol]], into two second messagers, [[inositol triphosphate]] and [[diglyceride|diacylglycerol]].<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00388 |title=Pfam entry: Phosphatidylinositol-specific phospholipase C, X domain |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929084148/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00388 |archive-date=2007-09-29 |url-status=dead }}</ref> || [[Lipid signaling]] ||core structure composed of a split [[triosephosphate isomerase]] (TIM) barrel which has an active site, catalytic residues, and a Ca<sup>2+</sup> binding site <ref>{{Citation |title=Phospholipase C |date=2023-08-16 |url=https://en.wikipedia.org/w/index.php?title=Phospholipase_C&oldid=1170655893 |work=Wikipedia |access-date=2023-11-29 |language=en}}</ref> 
|-
| [[Cholesterol oxidase]]s || [[Oxidize]]s and isomerizes [[cholesterol]] to cholest-4-en-3-one.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF09129 |title=Pfam entry: Cholesterol oxidase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929083056/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF09129 |archive-date=2007-09-29 |url-status=dead }}</ref> || Depletes [[cellular membrane]]s of cholesterol, used in bacterial [[pathogenesis]].||two loops of residue which act as a lid on the [[active site]]<ref>{{Cite journal |last1=Yue |first1=Q. Kimberley |last2=Kass |first2=Ignatius J. |last3=Sampson |first3=Nicole S. |last4=Vrielink |first4=Alice |date=1999-04-01 |title=Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants |url=https://pubs.acs.org/doi/10.1021/bi982497j |journal=Biochemistry |language=en |volume=38 |issue=14 |pages=4277–4286 |doi=10.1021/bi982497j |pmid=10194345 |issn=0006-2960}}</ref>
|-
| [[Carotenoid oxygenase]]|| Cleaves [[carotenoids]].<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF03055 |title=Pfam entry: Retinal pigment epithelial membrane protein |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929104832/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF03055 |archive-date=2007-09-29 |url-status=dead }}</ref>|| Carotenoids function in both plants and animals as [[hormone]]s (includes [[vitamin A]] in humans), [[pigment]]s, [[Flavor (taste)|flavor]]s, floral scents and defense compounds. ||composed of multiple enzymes attached together forming branch-like structures<ref>{{Citation |title=Carotenoid oxygenase |date=2023-11-29 |url=https://en.wikipedia.org/w/index.php?title=Carotenoid_oxygenase&oldid=1187404336 |work=Wikipedia |access-date=2023-11-29 |language=en}}</ref>
|-
| [[Lipoxygenase]]s || [[Iron]]-containing enzymes that [[catalyze]] the [[Lipoxygenase|dioxygenation]] of polyunsaturated [[fatty acid]]s.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00305 |title=Pfam entry: Lipoxygenase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929104653/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00305 |archive-date=2007-09-29 |url-status=dead }}</ref> ||In animals lipoxygenases are involved in the synthesis of [[inflammation|inflammatory]] mediators known as [[leukotrienes]].|| hundreds of [[amino acid]]s that makes up a protein are organized into two domains: beta-sheet N terminal and helical C terminal<ref>{{Cite journal |last1=Prigge |first1=S. T. |last2=Boyington |first2=J. C. |last3=Faig |first3=M. |last4=Doctor |first4=K. S. |last5=Gaffney |first5=B. J. |last6=Amzel |first6=L. M. |date=1997-11-01 |title=Structure and mechanism of lipoxygenases |journal=Biochimie |volume=79 |issue=11 |pages=629–636 |doi=10.1016/S0300-9084(97)83495-5 |issn=0300-9084|doi-access=free |pmid=9479444 }}</ref>
|-
| [[Clostridium perfringens alpha toxin|Alpha toxin]]s || Cleave [[phospholipid]]s in the cell membrane, similar to Phospholipase C.<ref>[http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1kho PDBsum entry: Alpha Toxin]</ref>|| Bacterial pathogenesis, particularly by ''[[Clostridium perfringens]]''. ||soluble monomer with oligomeric pre-pore complexes<ref>{{Cite web |title=Alpha Toxin - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/nursing-and-health-professions/alpha-toxin |access-date=2023-11-29 |website=www.sciencedirect.com}}</ref>
|-
| [[Sphingomyelinase]] C || A [[phosphodiesterase]], cleaves phosphodiester bonds.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01663 |title=Pfam entry: Type I phosphodiesterase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929084034/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01663 |archive-date=2007-09-29 |url-status=dead}}</ref> || Processing of lipids such as [[sphingomyelin]].||[[Saposin protein domain|saposin]] domain and connector regions with a metallophosphate catalytic domain <ref>{{Cite journal |last1=Xiong |first1=Zi-Jian |last2=Huang |first2=Jingjing |last3=Poda |first3=Gennady |last4=Pomès |first4=Régis |last5=Privé |first5=Gilbert G. |date=2016-07-31 |title=Structure of Human Acid Sphingomyelinase Reveals the Role of the Saposin Domain in Activating Substrate Hydrolysis |url=https://www.sciencedirect.com/science/article/pii/S0022283616302200 |journal=Journal of Molecular Biology |volume=428 |issue=15 |pages=3026–3042 |doi=10.1016/j.jmb.2016.06.012 |pmid=27349982 |issn=0022-2836}}</ref>
|-
| [[Glycosyltransferase]]s: MurG and Transglycosidases || Catalyzes the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming [[glycosidic]] bonds.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00534 |title=Pfam entry: Glycosyl transferases group 1 |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929120820/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00534 |archive-date=2007-09-29 |url-status=dead }}</ref> || Biosynthesis of [[disaccharide]]s, [[oligosaccharide]]s and [[polysaccharide]]s (glycoconjugates), MurG is involved in bacterial [[peptidoglycan]] biosynthesis. || three glycine rich loops: one in the C terminal and two in the N terminal <ref>{{Cite journal |last1=Ünligil |first1=Uluğ M |last2=Rini |first2=James M |date=2000-10-01 |title=Glycosyltransferase structure and mechanism |url=https://www.sciencedirect.com/science/article/pii/S0959440X0000124X |journal=Current Opinion in Structural Biology |volume=10 |issue=5 |pages=510–517 |doi=10.1016/S0959-440X(00)00124-X |pmid=11042447 |issn=0959-440X}}</ref> 
|-
| [[Ferrochelatase]] || Converts [[protoporphyrin IX]] into [[heme]].<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00762 |title=Pfam entry: Ferrochelatase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929120511/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00762 |archive-date=2007-09-29 |url-status=dead }}</ref> || Involved in [[porphyrin]] metabolism, [[protoporphyrin]]s are used to strengthen [[egg shell]]s. || [[polypeptide]] folded into two domains that each have a four-stranded parallel [[beta sheet]] flanked by alpha [[A-helices|helices]]<ref>{{Cite journal |last1=Al-Karadaghi |first1=Salam |last2=Hansson |first2=Mats |last3=Nikonov |first3=Stanislav |last4=Jönsson |first4=Bodil |last5=Hederstedt |first5=Lars |date=November 1997 |title=Crystal structure of ferrochelatase: the terminal enzyme in heme biosynthesis |journal=Structure |volume=5 |issue=11 |pages=1501–1510 |doi=10.1016/s0969-2126(97)00299-2 |issn=0969-2126|doi-access=free |pmid=9384565 }}</ref>
|-
| Myotubularin-related protein family || Lipid [[phosphatase]] that dephosphorylates [[Phosphatidylinositol 3-phosphate|PtdIns3P]] and [[Phosphatidylinositol (3,5)-bisphosphate|PtdIns(3,5)P2]].<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF06602 |title=Pfam entry:Myotubularin-related |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926215455/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF06602 |archive-date=2007-09-26 |url-status=dead }}</ref>|| Required for [[muscle]] cell differentiation. ||contains a [[GRAM domain]], [[SET domain|SET]] interacting domain, and a [[PDZ domain|PDZ]] binding domain<ref>{{Cite book |title=Emery and Rimoin's Principles and Practice of Medical Genetics |url=https://www.sciencedirect.com/book/9780123838346/emery-and-rimoins-principles-and-practice-of-medical-genetics |access-date=2023-11-29 |isbn=978-0-12-383834-6 |language=en}}</ref>
|-
| [[Dihydroorotate dehydrogenase]]s || [[Oxidation]] of dihydroorotate (DHO) to orotate.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01180 |title=Pfam entry:Dihydroorotate dehydrogenase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926220055/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01180 |archive-date=2007-09-26 |url-status=dead }}</ref>|| Biosynthesis of [[pyrimidine]] [[nucleotide]]s in [[prokaryotic]] and [[eukaryotic]] cells. ||composed of two domains: [[Alpha beta barrel|alpha/beta barrel]] domain that contains the active site and an [[alpha-helical]] domain that forms the opening tunnel to the active site <ref>{{Cite journal |last1=Liu |first1=Shenping |last2=Neidhardt |first2=Edie A |last3=Grossman |first3=Trudy H |last4=Ocain |first4=Tim |last5=Clardy |first5=Jon |date=January 2000 |title=Structures of human dihydroorotate dehydrogenase in complex with antiproliferative agents |journal=Structure |volume=8 |issue=1 |pages=25–33 |doi=10.1016/s0969-2126(00)00077-0 |issn=0969-2126|doi-access=free |pmid=10673429 }}</ref>
|-
|[[Glycolate oxidase]] || Catalyses the [[oxidation]] of α-[[hydroxycarboxylic acid]]s to the corresponding α-[[ketoacid]]s.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01070 |title=Pfam entry: FMN-dependent dehydrogenase |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929111635/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01070 |archive-date=2007-09-29 |url-status=dead }}</ref>|| In green [[plant]]s, the enzyme participates in [[photorespiration]]. In animals, the enzyme participates in production of [[oxalate]].||β8/α8 fold containing alpha helices, beta strands, and loops and turns<ref>{{Cite web |title=Glycolate oxidase - Proteopedia, life in 3D |url=https://proteopedia.org/wiki/index.php/Glycolate_oxidase#:~:text=The%20biological%20assembly%20of%20human,are%20shown%20as%20red%20spheres. |access-date=2023-11-28 |website=proteopedia.org |language=en}}</ref>
|}

===Membrane-targeting domains (“lipid clamps")===
[[Image:1ptr.png|thumb|right|170px| [[C1 domain]] of PKC-delta (1ptr)
Middle plane of the lipid bilayer – black dots. Boundary of the hydrocarbon core region – blue dots (cytoplasmic side). Layer of lipid phosphates – yellow dots.]]
Membrane-targeting domains associate specifically with head groups of their lipid ligands embedded into the membrane. These lipid ligands are present in different concentrations in distinct types of biological membranes (for example, [[Phosphatidylinositol 3-phosphate|PtdIns3P]] can be found mostly in membranes of early [[endosome]]s, [[Phosphatidylinositol (3,5)-bisphosphate|PtdIns(3,5)P2]] in late [[endosome]]s, and [[Phosphatidylinositol 4-phosphate|PtdIns4P]] in the [[Golgi apparatus|Golgi]]).<ref name="Cho"/> Hence, each domain is targeted to a specific membrane.
*[[C1 domain]]s and [[Phorbol|phorbol esters]].
*[[C2 domain]]s bind [[phosphatidylserine]], [[phosphatidylcholine]] or [[Phosphatidylinositol (3,4)-bisphosphate|PtdIns(3,4)P2]] or [[Phosphatidylinositol (4,5)-bisphosphate|PtdIns(4,5)P2]].
*[[Pleckstrin homology domain]]s, [[PX domain]]s, and [[Tubby protein|Tubby domains]]  bind different [[Phosphatidylinositol|phosphoinositides]]
*[[FYVE domain]]s are more specific for PtdIns3P.
*[[ENTH domain]]s bind [[Phosphatidylinositol (3,4)-bisphosphate|PtdIns(3,4)P2]] or [[Phosphatidylinositol (4,5)-bisphosphate|PtdIns(4,5)P2]].
*[[ANTH]] domain binds PtdIns(4,5)P2.
*Proteins from [[Merlin (protein)|ERM (ezrin/radixin/moesin) family]] bind PtdIns(4,5)P2.
*Other [[Phosphatidylinositol|phosphoinositide]]-binding proteins include [[phosphotyrosine]]-binding domain and certain [[PDZ domain]]s. They bind PtdIns(4,5)P2.
*Discoidin domains of blood [[coagulation]] factors
*[[ENTH]], VHS and [[ANTH]] domains

===Structural domains===
Structural domains mediate attachment of other proteins to membranes. Their binding to membranes can be mediated by [[calcium]] ions (Ca<sup>2+</sup>) that form bridges between the acidic protein residues and phosphate groups of lipids, as in annexins or GLA domains.

{| class="wikitable" style="margin: 1em auto 1em auto"
!width="150"|Class
!width="275"|Function
!width="305"| Physiology
!width="50"| Structure
|-
|[[Annexin]]s || [[Calcium]]-dependent intracellular membrane/ [[phospholipid]] binding.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00191 |title=Pfam entry: Annexin |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929104531/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00191 |archive-date=2007-09-29 |url-status=dead }}</ref> || Functions include [[Vesicle (biology)|vesicle]] trafficking, membrane fusion and [[ion channel]] formation.||
|-
|[[Synapsin|Synapsin I]]|| Coats [[synaptic vesicle]]s and binds to several [[cytoskeletal]] elements.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF02078 |title=Pfam entry Synapsin N |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926215343/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF02078 |archive-date=2007-09-26 |url-status=dead }}</ref>|| Functions in the regulation of [[neurotransmitter]] release.||
|-
|[[Synuclein]]|| Unknown cellular function.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01387 |title=Pfam entry Synuclein |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926215944/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF01387 |archive-date=2007-09-26 |url-status=dead }}</ref>|| Thought to play a role in regulating the stability and/or turnover of the [[plasma membrane]]. Associated with both [[Parkinson's disease]] and [[Alzheimer's disease]].||
|-
|GLA-domains of the [[coagulation|coagulation system]]|| [[Gamma-carboxyglutamate]] (GLA) domains are responsible for the high-affinity binding of calcium ions.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00594 |title=Pfam entry: Gla |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070929111243/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00594 |archive-date=2007-09-29 |url-status=dead }}</ref>|| Involved in function of clotting factors in the [[Coagulation#The coagulation cascade|blood coagulation cascade.]]||
|-
| [[Spectrin]] and α-[[actinin]]-2 || Found in several cytoskeletal and [[microfilament]] proteins.<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00435 |title=Pfam entry Spectrin |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926215853/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00435 |archive-date=2007-09-26 |url-status=dead }}</ref> || Maintenance of [[plasma membrane]] integrity and cytoskeletal structure.||
|}

===Transporters of small hydrophobic molecules===
These peripheral proteins function as carriers of non-polar compounds between different types of cell membranes or between membranes and cytosolic protein complexes. The transported substances are phosphatidylinositol, tocopherol, gangliosides, glycolipids, sterol derivatives, retinol, fatty acids, water, macromolecules, red blood cells, phospholipids, and nucleotides.
*[[Glycolipid transfer protein]]s
*[[Lipocalin]]s including [[retinol binding protein]]s and [[fatty acid]]-binding proteins
*Polyisoprenoid-binding protein, such as [[YceI protein domain]]
*[[Ganglioside GM2 activator protein]]s
*[[CRAL-TRIO domain]] (α-[[Tocopherol]] and [[phosphatidylinositol]] sec14p transfer proteins)
*[[Sterol carrier protein]]s
*[[Steroidogenic acute regulatory protein|Phosphatidylinositol transfer proteins and STAR domains]]
*[[Oxysterol-binding protein]]

===Electron carriers===
These proteins are involved in [[electron transport chain]]s. They include [[cytochrome c]], [[Copper proteins|cupredoxins]], [[iron–sulfur protein|high potential iron protein]], adrenodoxin reductase, some [[flavoprotein]]s, and others.

===Polypeptide hormones, toxins, and antimicrobial peptides===
Many hormones, [[neurotoxin|toxins]], [[Enzyme inhibitor|inhibitor]]s, or [[antimicrobial peptides]] interact specifically with [[transmembrane protein]] complexes. They can also accumulate at the lipid bilayer surface, prior to binding their protein targets. Such polypeptide ligands are often positively charged and interact [[Ionic bond|electrostatically]] with [[anionic]] membranes.

Some water-soluble proteins and peptides can also form [[Ion channel|transmembrane channel]]s. They usually undergo [[oligomer]]ization, significant [[conformational change]]s, and associate with membranes irreversibly. 3D structure of one such transmembrane channel, [[Hemolysis (microbiology)|α-hemolysin]], has been determined. In other cases, the experimental structure represents a water-soluble conformation that interacts with the lipid bilayer peripherally, although some of the channel-forming peptides are rather hydrophobic and therefore were studied by [[NMR spectroscopy]] in organic solvents or in the presence of [[micelles]].

{| class="wikitable" style="margin: 1em auto 1em auto"
!width="100"|Class
!width="275"|Proteins
!width="655"|Physiology
|-
| [[Venom]] [[toxin]]s ||
*[[Scorpion|Scorpion venom]]
*[[Snake venom]]
*[[Conotoxins]]
*[[Poneratoxin]] (insect)
|| Well known types of biotoxins include [[neurotoxins]], [[cytotoxin]]s, [[hemotoxin]]s and [[necrotoxin]]s. Biotoxins have two primary functions: predation ([[snake]], [[scorpion]] and [[cone snail]] toxins) and defense ([[honeybee]] and [[ant]] toxins).<ref>{{cite book | veditors = Rochat H, Martin-Eauclaire MF |title=Animal toxins: facts and protocols | url=https://books.google.com/books?id=kDDWg_oJYHIC&q=peptide+venom+toxin&pg=PA149| publisher=Birkhũser Verlag |location=Basel |year=2000 |isbn=3-7643-6020-8}}</ref>
|-
| [[Sea anemone]] toxins ||
*Sea anemone [[sodium channel]] inhibitory toxin
*[[Neurotoxin|Neurotoxin III]]
*[[Cytolysin]]s
||Inhibition of sodium and [[potassium channel]]s and [[Pore forming toxins|membrane pore formation]] are the primary actions of over 40 known Sea anemone peptide toxins. Sea anemone are [[carnivorous]] animals and use toxins in [[predation]] and defense; anemone toxin is of similar [[toxicity]] as the most toxic [[organophosphate]] [[chemical warfare]] agents.<ref>{{cite web | vauthors = Patocka J, Strunecka A | date = 1999 | url = http://www.asanltr.com/ASANews-99/991b.htm | title = Sea Anemone Toxins | archive-url = https://web.archive.org/web/20130615144536/http://www.asanltr.com/ASANews-99/991b.htm | archive-date= 15 June 2013 | work = The ASA Newsletter }}</ref>
|-
| [[Bacterial]] toxins ||
*[[Clostridium perfringens|Perfringolysin O]]
*[[Botulinum toxin]] B
*Heat-stable [[enterotoxin]] B
*δ-[[Endotoxin]]s
*[[Bacteriocin]]s, such as [[microcin]])
*[[Lantibiotic]] peptides, such as [[nisin]])
*[[Gramicidin S]]
||[[Microbial]] toxins are the primary [[virulence factor]]s for a variety of [[pathogenic]] bacteria. Some toxins, are [[Pore forming toxins]] that lyse cellular membranes. Other toxins inhibit [[Protein biosynthesis|protein synthesis]] or activate [[second messenger]] pathways causing dramatic alterations to [[signal transduction]] pathways critical in maintaining a variety of cellular functions. Several bacterial toxins can act directly on the [[immune system]], by acting as [[superantigen]]s and causing massive [[T cell]] [[Cell growth|proliferation]], which overextends the immune system. Botulinum toxin is a neurotoxin that prevents neuro-secretory vesicles from docking/fusing with the nerve [[synapse]] plasma membrane, inhibiting [[neurotransmitter]] release.<ref>{{cite journal | vauthors = Schmitt CK, Meysick KC, O'Brien AD | title = Bacterial toxins: friends or foes? | journal = Emerging Infectious Diseases | volume = 5 | issue = 2 | pages = 224–234 | year = 1999 | pmid = 10221874 | pmc = 2640701 | doi = 10.3201/eid0502.990206 }}</ref>
|-
| [[Fungal]] toxins ||
*Cyclic [[lipopeptide]] antibiotics<br/> [[Surfactin]] and [[daptomycin]]
*[[Peptaibol]]s
||These peptides are characterized by the presence of an unusual amino acid, [[2-Aminoisobutyric acid|α-aminoisobutyric acid]], and exhibit [[antibiotic]] and [[Fungicide|antifungal]] properties due to their membrane channel-forming activities.<ref>{{cite journal | vauthors = Chugh JK, Wallace BA | title = Peptaibols: models for ion channels | journal = Biochemical Society Transactions | volume = 29 | issue = Pt 4 | pages = 565–570 | date = August 2001 | pmid = 11498029 | doi = 10.1042/BST0290565 }}</ref>
|-
|[[Antimicrobial peptide]]s ||
*[[Helicobacter pylori|HP]] peptide
*[[Saposin]] B and [[NK-lysin]]
*[[Lactoferricin]] B
*[[Magainin]], and [[Pleurocidin]]
||The modes of action by which antimicrobial peptides kill bacteria is varied and includes disrupting membranes, interfering with [[metabolism]], and targeting [[cytoplasm]]ic components. In contrast to many conventional antibiotics these peptides appear to be [[bacteriocidal]] instead of [[bacteriostatic]].
|-
| [[Defensin]]s ||
*[[Insect defensin]]s
*[[Plant defensin]]s, including [[Cyclotides]] and [[thionin]]s
||Defensins are a type of antimicrobial peptide; and are an important component of virtually all [[innate immune system|innate host defenses]] against microbial invasion. Defensins penetrate microbial cell membranes by way of electrical attraction, and form a pore in the membrane allowing efflux, which ultimately leads to the lysis of microorganisms.<ref>{{cite journal | vauthors = Oppenheim JJ, Biragyn A, Kwak LW, Yang D | title = Roles of antimicrobial peptides such as defensins in innate and adaptive immunity | journal = Annals of the Rheumatic Diseases | volume = 62 | issue = Suppl 2 | pages = ii17–ii21 | date = November 2003 | pmid = 14532141 | pmc = 1766745 | doi = 10.1136/ard.62.suppl_2.ii17 }}</ref>
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| [[Neuronal]] peptides ||
*[[Tachykinin]] peptides
||These proteins excite neurons, evoke [[behavioral]] responses, are potent [[Vasodilation|vasodilatator]]s, and are responsible for contraction in many types of [[smooth muscle]].<ref>{{Cite web |url=http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF02202 |title=Pfam entry Tachykinin |access-date=2007-01-25 |archive-url=https://web.archive.org/web/20070926215842/http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF02202 |archive-date=2007-09-26 |url-status=dead}}</ref>
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| [[Apoptosis]] regulators ||
*[[Bcl-2]]
|| Members of the Bcl-2 family govern [[mitochondria]]l outer membrane permeability. Bcl-2 itself suppresses apoptosis in a variety of cell types including [[lymphocyte]]s and [[neurons|neuronal cell]]s.
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