component of the complement cascade for immune response; may be a component of the membrane attack complex [RGD, Feb 2006]

Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells. C7 serves as a membrane anchor ().

Also known as Complement component C8 alpha chain (Complement component 8 subunit alpha).
C8A: Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells. C8A inserts into the target membrane, but does not form pores by itself. Defects in C8A are a cause of complement component 8 deficiency type 1 (C8D1). A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis. Belongs to the complement C6/C7/C8/C9 family.

Protein type: Membrane protein, multi-pass

Cellular Component: extracellular region; extracellular space; membrane attack complex

Molecular Function: complement binding; protein complex binding

Biological Process: complement activation; cytolysis

Also known as Complement component C8 beta chain (Complement component 8 subunit beta).
C8B: Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells. Defects in C8B are a cause of complement component 8 deficiency type 2 (C8D2). A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis. Belongs to the complement C6/C7/C8/C9 family.

Protein type: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 1p32.2

Cellular Component: extracellular region; membrane

Biological Process: complement activation; immune response; regulation of complement activation

Disease: Complement Component 8 Deficiency, Type Ii

C8G: C8 is a constituent of the membrane attack complex. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol. Belongs to the calycin superfamily. Lipocalin family.

Protein type: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 9q34.3

Cellular Component: extracellular region

Biological Process: regulation of complement activation

C9: Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells. C9 is the pore-forming subunit of the MAC. Defects in C9 are a cause of complement component 9 deficiency (C9D). A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis. Belongs to the complement C6/C7/C8/C9 family.

Protein type: Apoptosis; Extracellular matrix; Membrane protein, integral; Membrane protein, multi-pass

Chromosomal Location of Human Ortholog: 5p14-p12

Cellular Component: cytoplasm; extracellular region; integral to plasma membrane; plasma membrane

Biological Process: hemolysis by symbiont of host red blood cells; regulation of complement activation

Disease: Complement Component 9 Deficiency; Macular Degeneration, Age-related, 15