Complement Component C1ra Products

Description

C1rA (complement component 1 subcomponent r-A) is an 85-95 kDa member of the peptidase S1 family of enzymes. It is secreted primarily hepatocytes but is also known to be expressed by monocytes, fibroblasts, keratinocytes and endothelial cells. C1r forms a key component of the complement 1 complex. Complement is a general name for a group of molecules that "complement" the antimicrobial effort associated with antibodies and phagocytic cells. The C1 complex is composed of five proteins; one C1q that binds immunoglobulin, and two copies of two inactive serine proteases termed C1r and C1s. Activation of the C1 complex is the first step in a proteolytic cascade that generates multiple modulators involved in cell lysis and phagocytosis. Following C1q binding, each 85-90 kDa C1r monomer undergoes autocleavage to generate a 60 kDa and 28-34 kDa disulfide‑linked enzymatically-active heterodimer. Each C1r heterodimer now acts on a C1s counterpart to create a globally-active complex that drives the complement cascade. In contrast to human, the mouse genes for C1r and C1s have undergone duplication. The major, or liver derived, C1r is termed C1rA, while a prostate-associated C1r is called C1rB. Mouse C1rA proenzyme is 691 amino acids (aa) in length (aa 17-707) (SwissProt #: Q8CG16). It contains one CUB domain (aa 17-140), an EGF-like motif (aa 141-189), a second CUB domain (aa 192-303), two SUSHI (or CCP) repeats (aa 306-448), and a C-terminal peptidase S1 region (aa 463-704). Autocleavage occurs between Arg462:Ile463, generating a 60 kDa N-terminal subunit that is disulfide‑linked to a 30 kDa enzymatic subunit. Over aa 17-707, mouse C1rA shares 91% and 82% aa sequence identity with rat and human C1r, respectively. Full-length mouse C1rA shares 96% aa sequence identity with mouse C1rB, with virtually all differences arising in the enzymatic, or small subunit.

Bioinformatics

Uniprot	AAH04637
Product By Gene ID	50909
Alternate Names	C1r;Complement C1r-A subcomponent;mC1;mC1rA;Peptidase S1 domain-containing protein C1ra Complement Component C1ra