Complement component 5: Difference between revisions

Latest revision as of 05:32, 16 February 2025

Complement Component 5[edit]

Complement Component 5 (C5) is a crucial protein in the complement system, which is part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen's cell membrane. C5 plays a pivotal role in the formation of the membrane attack complex (MAC), which is essential for the lysis of pathogens.

Structure[edit]

C5 is a large glycoprotein composed of two chains, the alpha and beta chains, linked by a disulfide bond. The protein is synthesized in the liver and circulates in the blood as an inactive precursor. Upon activation, C5 is cleaved into two fragments: C5a and C5b.

Function[edit]

The primary function of C5 is to initiate the formation of the MAC. The cleavage of C5 into C5a and C5b is a critical step in the complement cascade.

C5a: This is a potent anaphylatoxin that acts as a powerful chemotactic factor, attracting neutrophils and other immune cells to the site of infection. It also increases vascular permeability and induces smooth muscle contraction.
C5b: This fragment initiates the assembly of the MAC by binding sequentially to C6, C7, C8, and multiple C9 molecules, forming a pore in the target cell membrane, leading to cell lysis.

Role in Disease[edit]

Dysregulation of C5 can lead to various diseases. Overactivation of C5 can contribute to autoimmune diseases and chronic inflammatory conditions, while deficiencies in C5 can result in increased susceptibility to infections, particularly by Neisseria species.

Therapeutic Target[edit]

C5 is a target for therapeutic intervention in diseases characterized by excessive complement activation. Eculizumab, a monoclonal antibody that inhibits C5, is used in the treatment of conditions such as paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.

Related Pages[edit]

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-'''Complement component 5''' (C5) is a [[protein]] that is part of the [[complement system]], a complex system of proteins that play a crucial role in the [[immune system]] and inflammation. C5 is produced by the liver and is found in the blood plasma. It is involved in a variety of immune responses, including the promotion of inflammation, the attraction of white blood cells to sites of infection, and the destruction of bacteria and other foreign substances.
+{{DISPLAYTITLE:Complement Component 5}}
-== Structure ==
+== Complement Component 5 ==
-C5 is a large protein composed of multiple subunits. It is made up of a heavy chain and a light chain, which are linked together by disulfide bonds. The heavy chain contains a region known as the C5 convertase binding site, which is crucial for the activation of C5.
+[[File:Formowanie_MAC-en.svg|thumb|right|300px|Formation of the Membrane Attack Complex (MAC) involving Complement Component 5]]
-== Function ==
+Complement Component 5 (C5) is a crucial protein in the [[complement system]], which is part of the [[immune system]] that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen's cell membrane. C5 plays a pivotal role in the formation of the [[membrane attack complex]] (MAC), which is essential for the lysis of pathogens.
-The primary function of C5 is to initiate the formation of the [[Membrane Attack Complex]] (MAC), a group of proteins that form a pore in the membrane of invading pathogens, leading to their destruction. This process is known as [[complement activation]].
-C5 is also involved in the process of [[chemotaxis]], the attraction of white blood cells to sites of infection. It does this by being cleaved into two smaller fragments, C5a and C5b. C5a is a potent chemotactic factor, meaning it can attract white blood cells to the site of infection. C5b, on the other hand, is involved in the formation of the MAC.
+=== Structure ===
+C5 is a large glycoprotein composed of two chains, the alpha and beta chains, linked by a disulfide bond. The protein is synthesized in the liver and circulates in the blood as an inactive precursor. Upon activation, C5 is cleaved into two fragments: C5a and C5b.
-== Clinical significance ==
+=== Function ===
-Mutations in the C5 gene can lead to a variety of health problems. For example, a deficiency in C5 can result in an increased susceptibility to certain types of bacterial infections. On the other hand, overactivity of C5 has been implicated in a number of inflammatory diseases, including [[rheumatoid arthritis]], [[lupus]], and [[asthma]].
+The primary function of C5 is to initiate the formation of the MAC. The cleavage of C5 into C5a and C5b is a critical step in the complement cascade.
-There are also drugs that target C5, such as [[eculizumab]], which is used to treat conditions like [[paroxysmal nocturnal hemoglobinuria]] and [[atypical hemolytic uremic syndrome]].
+* '''C5a''': This is a potent [[anaphylatoxin]] that acts as a powerful [[chemotactic factor]], attracting [[neutrophils]] and other immune cells to the site of infection. It also increases vascular permeability and induces smooth muscle contraction.
+* '''C5b''': This fragment initiates the assembly of the MAC by binding sequentially to C6, C7, C8, and multiple C9 molecules, forming a pore in the target cell membrane, leading to cell lysis.
-== See also ==
+=== Role in Disease ===
+Dysregulation of C5 can lead to various diseases. Overactivation of C5 can contribute to [[autoimmune diseases]] and chronic inflammatory conditions, while deficiencies in C5 can result in increased susceptibility to infections, particularly by [[Neisseria]] species.
+=== Therapeutic Target ===
+C5 is a target for therapeutic intervention in diseases characterized by excessive complement activation. [[Eculizumab]], a monoclonal antibody that inhibits C5, is used in the treatment of conditions such as [[paroxysmal nocturnal hemoglobinuria]] and [[atypical hemolytic uremic syndrome]].
+== Related Pages ==
 * [[Complement system]]
-* [[Membrane Attack Complex]]
+* [[Membrane attack complex]]
-* [[Complement activation]]
+* [[Anaphylatoxin]]
-* [[Chemotaxis]]
+* [[Eculizumab]]
-[[Category:Proteins]]
-[[Category:Immune system]]
 [[Category:Complement system]]
-{{protein-stub}}
-{{medicine-stub}}