Human complement protein C8 gamma.
Human C8 gamma is a 22 kDa subunit of complement component C8, which is one of five components (C5b, C6, C7, C8, C9) that interact to form the cytolytic membrane attack complex (MAC) of complement. C8 contains three nonidentical subunits (alpha, beta, gamma) that are products of different genes. These subunits are arranged asymmetrically to form a disulfide-linked C8 alpha-gamma dimer that is noncovalently associated with C8 beta. C8 alpha and C8 beta are homologous to C6, C7 and C9 and together these proteins comprise what is referred to as the 'MAC protein family'. By comparison, C8 gamma is distinct in that it belongs to the lipocalin family of small, secreted proteins which have the common ability to bind small hydrophobic ligands. While specific roles have been identified for C8 alpha and C8 beta in the formation and function of the MAC, a function for C8 gamma and the identity of its ligand are unknown. This review summarizes the current status of C8 gamma structure and function and the progress made from efforts to determine its role in the complement system.
Schreck
S F
SF
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
Parker
C
C
Plumb
M E
ME
Sodetz
J M
JM
D000595:Amino Acid Sequence; D003185:Complement C8 / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015938:Complement Membrane Attack Complex; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D011487:Protein Conformation
C087169:C8G protein, human; D003185:Complement C8; D015938:Complement Membrane Attack Complex