C4

16D2

C4 plays a central role in the activation of the classical pathway of the complement system. It is processed by activated C1 which removes from the alpha chain the C4a anaphylatoxin. The remaining alpha chain fragment C4b is the major activation product and is an essential subunit of the C3 convertase (C4b2a) and the C5 convertase (C3bC4b2a) enzymes of the classical complement pathway.

Secreted.

C4 is a major histocompatibility complex class-III protein.

Contains 1 NTR domain. [1] Ogata R. T. and Zepf N. E. et al. C4 from C4-high and C4-low mouse strains have identical sequences in the region corresponding to the isotype-specific segment of human C4[2] Sepich D. S. Noonan D. J. Ogata R. T. Complete cDNA sequence of the fourth component of murine complement. [3] Ogata R. T. Rosa P. A. Zepf N. E. Sequence of the gene for murine complement component C4. [4] Nonaka M. Nakayama K. Yeul Y. D. Takahashi M. Complete nucleotide and derived amino acid sequences of the fourth component of mouse complement (C4). Evolutionary aspects. [5] Xie T. Rowen L. Aguado B. Ahearn M. E. Madan A. Qin S. Campbell R. D. Hood L. Analysis of the gene-dense major histocompatibility complex class III region and its comparison to mouse. [6] Carninci P. Kasukawa T. Katayama S. Gough J. Frith M. C. Maeda N. Oyama R. Ravasi T. Lenhard B. Wells C. et al. The transcriptional landscape of the mammalian genome. [7] Nonaka M. Nakayama K. Yeul Y. D. Shimizu A. Takahashi M. Molecular cloning and characterization of complementary and genomic DNA clones for mouse C4 and Slp. [8] Nonaka M. Kimura H. Yeul Y. D. Yokoyama S. Nakayama K. Takahashi M. Identification of the 5\' -flanking regulatory region responsible for the difference in transcriptional control between mouse complement C4 and Slp genes. [9] Hemenway C. Kalff M. Stavenhagen J. Walthall D. Robins D. Sequence comparison of alleles of the fourth component of complement (C4) and sex-limited protein (Slp). [10] Nonaka M. Takahashi M. Natsuume-Sakai S. Nonaka M. Tanaka S. Shimizu A. Honjo T. Isolation of cDNA clones specifying the fourth component of mouse complement and its isotype sex-limited protein.