C1r deficiency

Gene Information


HUGO name: C1R


  • Complement component 1, r subcomponent
  • Complement C1r component precursor


Reference sequences

Chromosomal location


Protein Information


Protein function:

C1r b chain is a serine protease that combines with C1q and C1s to form C1, the first component of the classical pathway of the complement system.

Catalytic activity:

Activates C1s by proteolytic cleavage so that it can, in turn, activate C2 and C4.


C1 is a calcium-dependent trimolecular complex of C1q, r and s in the molar ration of 1:2:2. C1r is a dimer of identical chains, each of which is activated by cleavage into two chains, a and b, connected by disulfide bonds.

Structures (PDB)

1APQ Structure Of The Egf-Like Module Of Human C1R, NMR, 19 Structures


Expression pattern for human

Tissue Expression (%) Clones
lymph node 17.52 1:125
thyroid gland 9.64 5:1136
skin, normal, 4 pooled samples 5.81 1:377
eye, cornea 4.86 1:451
mammary gland 4.56 3:1441
head/neck 4.20 1:522
gall bladder 3.60 4:2435
normal head/neck tissue 3.39 2:1292
subchondral bone 3.29 2:1332
brain, meningioma 3.09 1:709

Animal models



C. elegans