Complement component 5a

complement component 5
Schematic representation of three-dimensional structure of complement 5a
Identifiers
SymbolC5
NCBI gene727
HGNC1331
OMIM120900
RefSeqNM_001735
UniProtP01031
Other data
LocusChr. 9 q34.1
Search for
StructuresSwiss-model
DomainsInterPro

C5a is a protein fragment released from cleavage of complement component C5 by protease C5-convertase into C5a and C5b fragments. C5b is important in late events of the complement cascade, an orderly series of reactions which coordinates several basic defense mechanisms, including formation of the membrane attack complex (MAC), one of the most basic weapons of the innate immune system, formed as an automatic response to intrusions from foreign particles and microbial invaders. It essentially pokes microscopic pinholes in these foreign objects, causing loss of water and sometimes death. C5a, the other cleavage product of C5, acts as a highly inflammatory peptide, encouraging complement activation, formation of the MAC, attraction of innate immune cells, and histamine release involved in allergic responses. The origin of C5 is in the hepatocyte, but its synthesis can also be found in macrophages, where it may cause local increase of C5a. C5a is a chemotactic agent and an anaphylatoxin; it is essential in the innate immunity but it is also linked with the adaptive immunity. The increased production of C5a is connected with a number of inflammatory diseases.[1]

  1. ^ Manthey HD, Woodruff TM, Taylor SM, Monk PN (November 2009). "Complement component 5a (C5a)". The International Journal of Biochemistry & Cell Biology. 41 (11): 2114–2117. doi:10.1016/j.biocel.2009.04.005. PMID 19464229.