Complement component 1s explained

Complement component 1s (C1 esterase, activated complement C1s, complement C overbar 1r, C1s) is a protein involved in the complement system. C1s is part of the C1 complex.^{[1] [2] [3] [4]} In humans, it is encoded by the C1S gene.^[5]

C1s cleaves C4 and C2, which eventually leads to the production of the classical pathway C3-convertase.

See also

• C1q - another part of the C1 complex
• C1r - another part of the C1 complex
• MASP-2 - a protein similar to C1s, part of the lectin pathway

Further reading

• Luo C, Thielens NM, Gagnon J, Gal P, Sarvari M, Tseng Y, Tosi M, Zavodszky P, Arlaud GJ, Schumaker VN . Recombinant human complement subcomponent C1s lacking beta-hydroxyasparagine, sialic acid, and one of its two carbohydrate chains still reassembles with C1q and C1r to form a functional C1 complex . Biochemistry . 31 . 17 . 4254–62 . May 1992 . 1533159 . 10.1021/bi00132a015 .
• Illy C, Thielens NM, Gagnon J, Arlaud GJ . Effect of lactoperoxidase-catalyzed iodination on the Ca(2+)-dependent interactions of human C1s. Location of the iodination sites . Biochemistry . 30 . 29 . 7135–41 . July 1991 . 1854725 . 10.1021/bi00243a014 .
• Hess D, Schaller J, Rickli EE . Identification of the disulfide bonds of human complement C1s . Biochemistry . 30 . 11 . 2827–33 . March 1991 . 2007122 . 10.1021/bi00225a014 .
• Thielens NM, Van Dorsselaer A, Gagnon J, Arlaud GJ . Chemical and functional characterization of a fragment of C1-s containing the epidermal growth factor homology region . Biochemistry . 29 . 14 . 3570–8 . April 1990 . 2141278 . 10.1021/bi00466a021 .
• Busby TF, Ingham KC . NH2-terminal calcium-binding domain of human complement C1s- mediates the interaction of C1r- with C1q . Biochemistry . 29 . 19 . 4613–8 . May 1990 . 2372546 . 10.1021/bi00471a016 .
• Kusumoto H, Hirosawa S, Salier JP, Hagen FS, Kurachi K . Human genes for complement components C1r and C1s in a close tail-to-tail arrangement . Proceedings of the National Academy of Sciences of the United States of America . 85 . 19 . 7307–11 . October 1988 . 2459702 . 282175 . 10.1073/pnas.85.19.7307 . 1988PNAS...85.7307K . free .
• Katz Y, Strunk RC . Synthesis and regulation of C1 inhibitor in human skin fibroblasts . Journal of Immunology . 142 . 6 . 2041–5 . March 1989 . 10.4049/jimmunol.142.6.2041 . 2537870 . free .
• Tosi M, Duponchel C, Meo T, Couture-Tosi E . Complement genes C1r and C1s feature an intronless serine protease domain closely related to haptoglobin . Journal of Molecular Biology . 208 . 4 . 709–14 . August 1989 . 2553984 . 10.1016/0022-2836(89)90161-7 .
• Tosi M, Duponchel C, Meo T, Julier C . Complete cDNA sequence of human complement Cls and close physical linkage of the homologous genes Cls and Clr . Biochemistry . 26 . 26 . 8516–24 . December 1987 . 2831944 . 10.1021/bi00400a004 .
• Nguyen VC, Tosi M, Gross MS, Cohen-Haguenauer O, Jegou-Foubert C, de Tand MF, Meo T, Frézal J . Assignment of the complement serine protease genes C1r and C1s to chromosome 12 region 12p13 . Human Genetics . 78 . 4 . 363–8 . April 1988 . 2834284 . 10.1007/BF00291737 . 30582112 .
• Spycher SE, Nick H, Rickli EE . Human complement component C1s. Partial sequence determination of the heavy chain and identification of the peptide bond cleaved during activation . European Journal of Biochemistry . 156 . 1 . 49–57 . April 1986 . 3007145 . 10.1111/j.1432-1033.1986.tb09546.x . free .
• Mackinnon CM, Carter PE, Smyth SJ, Dunbar B, Fothergill JE . Molecular cloning of cDNA for human complement component C1s. The complete amino acid sequence . European Journal of Biochemistry . 169 . 3 . 547–53 . December 1987 . 3500856 . 10.1111/j.1432-1033.1987.tb13644.x . free .
• Kauffman D, Hofmann T, Bennick A, Keller P . Basic proline-rich proteins from human parotid saliva: complete covalent structures of proteins IB-1 and IB-6 . Biochemistry . 25 . 9 . 2387–92 . May 1986 . 3521730 . 10.1021/bi00357a013 .
• Bock SC, Skriver K, Nielsen E, Thøgersen HC, Wiman B, Donaldson VH, Eddy RL, Marrinan J, Radziejewska E, Huber R . Human C1 inhibitor: primary structure, cDNA cloning, and chromosomal localization . Biochemistry . 25 . 15 . 4292–301 . July 1986 . 3756141 . 10.1021/bi00363a018 .
• Carter PE, Dunbar B, Fothergill JE . The serine proteinase chain of human complement component C1s. Cyanogen bromide cleavage and N-terminal sequences of the fragments . The Biochemical Journal . 215 . 3 . 565–71 . December 1983 . 6362661 . 1152437 . 10.1042/bj2150565 .
• Nilsson T, Sjöholm I, Wiman B . Structural and circular-dichroism studies on the interaction between human C1-esterase inhibitor and C1s . The Biochemical Journal . 213 . 3 . 617–24 . September 1983 . 6604523 . 1152176 . 10.1042/bj2130617 .
• Rossi V, Gaboriaud C, Lacroix M, Ulrich J, Fontecilla-Camps JC, Gagnon J, Arlaud GJ . Structure of the catalytic region of human complement protease C1s: study by chemical cross-linking and three-dimensional homology modeling . Biochemistry . 34 . 22 . 7311–21 . June 1995 . 7779774 . 10.1021/bi00022a004 .
• Bersch B, Hernandez JF, Marion D, Arlaud GJ . Solution structure of the epidermal growth factor (EGF)-like module of human complement protease C1r, an atypical member of the EGF family . Biochemistry . 37 . 5 . 1204–14 . February 1998 . 9477945 . 10.1021/bi971851v .
• Endo Y, Takahashi M, Nakao M, Saiga H, Sekine H, Matsushita M, Nonaka M, Fujita T . Two lineages of mannose-binding lectin-associated serine protease (MASP) in vertebrates . Journal of Immunology . 161 . 9 . 4924–30 . November 1998 . 10.4049/jimmunol.161.9.4924 . 9794427 . free .
• Inoue N, Saito T, Masuda R, Suzuki Y, Ohtomi M, Sakiyama H . Selective complement C1s deficiency caused by homozygous four-base deletion in the C1s gene . Human Genetics . 103 . 4 . 415–8 . October 1998 . 9856483 . 10.1007/s004390050843 . 7689382 .

Notes and References

1. Book: Sim RB . The human complement system serine proteases and their proenzymes . Proteolytic Enzymes, Part C . Methods in Enzymology . 80 Pt C . 26–42 . 1981 . 6281620 . 10.1016/s0076-6879(81)80006-7 . 9780121819804 .
2. Mackinnon CM, Carter PE, Smyth SJ, Dunbar B, Fothergill JE . Molecular cloning of cDNA for human complement component C1s. The complete amino acid sequence . European Journal of Biochemistry . 169 . 3 . 547–53 . December 1987 . 3500856 . 10.1111/j.1432-1033.1987.tb13644.x . free .
3. Müller-Eberhard HJ . Molecular organization and function of the complement system . Annual Review of Biochemistry . 57 . 321–47 . 1988 . 3052276 . 10.1146/annurev.bi.57.070188.001541 .
4. Skoog MT, Mehdi S, Wiseman JS, Bey P . The specificity of two proteinases that cleave adjacent to arginine, C1 esterase and acrosin, for peptide p-nitroanilide substrates . Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology . 996 . 1–2 . 89–94 . June 1989 . 2500154 . 10.1016/0167-4838(89)90099-x .
5. Web site: Entrez Gene: C1S Complement component 1, s subcomponent.