Complement component 4 is a protein involved in the complement system.
It is cleaved into proteins 4a and 4b; 4b can be further cleaved into 4c and 4d.
Classical pathway. (Some labels are in Polish.)
It is responsible for the Chido Rodgers blood group system.
C4d has been identified as a biomarker for systemic lupus erythematosus.
- ^ http://www.immunologyreport.com/ATC2013/pdf/MacConmara.pdf
- ^ Chido Rodgers blood group system at BGMUT Blood Group Antigen Gene Mutation Database at NCBI, NIH
- ^ Liu CC, Manzi S, Kao AH, Navratil JS, Ruffing MJ, Ahearn JM (2005). "Reticulocytes bearing C4d as biomarkers of disease activity for systemic lupus erythematosus". Arthritis Rheum. 52 (10): 3087–99. doi:10.1002/art.21305. PMID 16200588.