Complement C4 from human serum has been used in mannose binding lectin (MBL) complex assay of serum samples and in MBL-associated serine proteases based C4 activation assay of plasma samples.
Complement C4 is mapped to human chromosome 6p21.33. It exists in two isoforms as c4A and c4B. C4 is a 200 kDa protein belonging to α2 macroglobulin (α2M) family. It undergoes posttranslational modification like sulfation and glycosylation and finally proteolysis to become a mature protein.
Variation in the copy number of the complement C4 gene alters the complement c4A and c4B levels in age-related macular degeneration (AMD) and increases risk of developing schizophrenia.
