Toxalbumin: Difference between revisions

Latest revision as of 05:27, 16 February 2025

Toxalbumin[edit]

Toxalbumins are a class of plant proteins that are highly toxic. These proteins are capable of inhibiting protein synthesis in eukaryotic cells, leading to cell death. Toxalbumins are found in several plant species, most notably in the seeds of the castor oil plant (Ricinus communis) and the jequirity bean (Abrus precatorius).

Structure and Function[edit]

Toxalbumins are ribosome-inactivating proteins (RIPs) that consist of two subunits: an A chain and a B chain. The A chain is an enzyme that depurinates a specific adenine residue in the 28S ribosomal RNA, thereby halting protein synthesis. The B chain is a lectin that binds to cell surface glycoproteins and facilitates the entry of the A chain into the cell.

Mechanism of Action[edit]

Once inside the cell, the A chain of the toxalbumin enzymatically removes an adenine base from the 28S rRNA of the ribosome. This action prevents the binding of elongation factors necessary for translation, effectively stopping protein synthesis and leading to cell death. The high toxicity of toxalbumins is due to their ability to inactivate a large number of ribosomes with a single molecule.

Notable Toxalbumins[edit]

Ricin[edit]

Ricin is one of the most well-known toxalbumins, derived from the seeds of the castor oil plant. It is highly toxic and has been studied for its potential use in bioterrorism. Ricin is a potent inhibitor of protein synthesis and can cause severe organ failure and death if ingested, inhaled, or injected.

Abrin[edit]

Abrin is another potent toxalbumin found in the seeds of the jequirity bean. Similar to ricin, abrin inhibits protein synthesis by depurinating the 28S rRNA. It is highly toxic and can cause severe gastrointestinal distress, organ damage, and death.

Medical Implications[edit]

Due to their high toxicity, toxalbumins have been studied for their potential use in cancer therapy. Researchers are investigating ways to target toxalbumins specifically to cancer cells, sparing healthy cells and minimizing side effects. However, the use of toxalbumins in medicine is still largely experimental.

Related Pages[edit]

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-'''Toxalbumin''' is a type of [[protein]] that is toxic and can be found in certain [[plant]] and [[bacteria]] species. These proteins can cause damage to the [[cell membrane]], leading to cell death. They are a type of [[lectin]], and can bind to specific sugar molecules on the surface of cells.
+== Toxalbumin ==
-== History ==
+[[File:Illustration_Ricinus_communis0.jpg|thumb|right|Illustration of ''Ricinus communis'', a plant containing the toxalbumin ricin.]]
-The term "toxalbumin" was first used in the late 19th century to describe plant proteins that had toxic effects. The first toxalbumin to be discovered was [[abrin]], a protein found in the seeds of the ''[[Abrus precatorius]]'' plant. This was followed by the discovery of [[ricin]], a similar protein found in the seeds of the ''[[Ricinus communis]]'' plant.
+'''Toxalbumins''' are a class of [[plant]] [[protein]]s that are highly toxic. These proteins are capable of inhibiting [[protein synthesis]] in [[eukaryotic cells]], leading to cell death. Toxalbumins are found in several plant species, most notably in the seeds of the [[castor oil plant]] (''[[Ricinus communis]]'') and the [[jequirity bean]] (''[[Abrus precatorius]]'').
-== Structure and function ==
+== Structure and Function ==
-Toxalbumins are typically composed of two [[polypeptide]] chains, referred to as the A-chain and the B-chain. The A-chain has [[enzymatic]] activity, while the B-chain is responsible for binding to specific sugar molecules on the surface of cells.
+Toxalbumins are [[ribosome-inactivating proteins]] (RIPs) that consist of two subunits: an A chain and a B chain. The A chain is an [[enzyme]] that depurinates a specific [[adenine]] residue in the [[28S ribosomal RNA]], thereby halting protein synthesis. The B chain is a [[lectin]] that binds to cell surface [[glycoproteins]] and facilitates the entry of the A chain into the cell.
-Once a toxalbumin has bound to a cell, it is taken up by the cell and the A-chain is released into the [[cytoplasm]]. The A-chain then inactivates the cell's [[ribosomes]], preventing protein synthesis and leading to cell death.
+== Mechanism of Action ==
-== Examples ==
+Once inside the cell, the A chain of the toxalbumin enzymatically removes an adenine base from the 28S rRNA of the [[ribosome]]. This action prevents the binding of [[elongation factors]] necessary for [[translation (biology)|translation]], effectively stopping protein synthesis and leading to cell death. The high toxicity of toxalbumins is due to their ability to inactivate a large number of ribosomes with a single molecule.
-In addition to abrin and ricin, other examples of toxalbumins include:
+== Notable Toxalbumins ==
-* [[Modeccin]], found in the ''[[Adenia digitata]]'' plant
+=== Ricin ===
-* [[Volksin]], found in the ''[[Adenia volkensii]]'' plant
-* [[Crotin]], found in the seeds of the ''[[Croton tiglium]]'' plant
-== Toxicity ==
+[[Ricin]] is one of the most well-known toxalbumins, derived from the seeds of the castor oil plant. It is highly toxic and has been studied for its potential use in [[bioterrorism]]. Ricin is a potent inhibitor of protein synthesis and can cause severe [[organ failure]] and death if ingested, inhaled, or injected.
-Toxalbumins are highly toxic and can cause severe illness or death if ingested or inhaled. Symptoms of toxalbumin poisoning can include nausea, vomiting, abdominal pain, and in severe cases, organ failure and death.
+=== Abrin ===
-== Treatment ==
+[[Abrin]] is another potent toxalbumin found in the seeds of the jequirity bean. Similar to ricin, abrin inhibits protein synthesis by depurinating the 28S rRNA. It is highly toxic and can cause severe [[gastrointestinal]] distress, [[organ damage]], and death.
-There is currently no specific antidote for toxalbumin poisoning. Treatment typically involves supportive care, including hydration and symptom management. In some cases, [[antibody]] therapy may be used to neutralize the toxalbumin.
+== Medical Implications ==
-== See also ==
+Due to their high toxicity, toxalbumins have been studied for their potential use in [[cancer therapy]]. Researchers are investigating ways to target toxalbumins specifically to cancer cells, sparing healthy cells and minimizing side effects. However, the use of toxalbumins in medicine is still largely experimental.
-* [[Protein toxicity]]
+== Related Pages ==
-* [[Plant toxins]]
-* [[Bacterial toxins]]
+* [[Ricinus communis]]
+* [[Abrus precatorius]]
+* [[Ribosome-inactivating protein]]
+* [[Protein synthesis]]
+* [[Bioterrorism]]
 [[Category:Toxins]]
 [[Category:Proteins]]
 [[Category:Plant toxins]]
-[[Category:Bacterial toxins]]
-{{stub}}