Reviewed, UniProtKB/Swiss-Prot P09871 (C1S_HUMAN)

Names and origin

Protein names

Recommended name:
    Complement C1s subcomponent
    EC=3.4.21.42
Alternative name(s):
    C1 esterase
Cleaved into the following 2 chains:
    1- Recommended name:
            Complement C1s subcomponent heavy chain
    2- Recommended name:
            Complement C1s subcomponent light chain

Gene names

Name:

C1S

Organism

Homo sapiens (Human) [Complete proteome]

Taxonomic identifier

9606 [NCBI]

Taxonomic lineage

Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Primates › Haplorrhini › Catarrhini › Hominidae › Homo

Protein attributes

Sequence length	688 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	C1s 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. C1r activates C1s so that it can, in turn, activate C2 and C4.
Catalytic activity	Cleavage of Arg-|-Ala bond in complement component C4 to form C4a and C4b, and Lys(or Arg)-|-Lys bond in complement component C2 to form C2a and C2b: the 'classical' pathway C3 convertase. Ref.13
Enzyme regulation	Inhibited by SERPING1. Ref.13
Subunit structure	C1 is a calcium-dependent trimolecular complex of C1q, C1r and C1s in the molar ration of 1:2:2. Activated C1s is an disulfide-linked heterodimer of a heavy chain and a light chain. Ref.11
Post-translational modification	The iron and 2-oxoglutarate dependent 3-hydroxylation of aspartate and asparagine is (R) stereospecific within EGF domains.
Involvement in disease	Defects in C1S are the cause of selective C1s deficiency [MIM:120580]; that is associated with early onset multiple autoimmune diseases. Ref.14
Sequence similarities	Belongs to the peptidase S1 family. Contains 2 CUB domains. Contains 1 EGF-like domain. Contains 1 peptidase S1 domain. Contains 2 Sushi (CCP/SCR) domains.
Biophysicochemical properties	Kinetic parameters: Less efficient than MASP2 in C4 cleavage. KM=12.3 µM for complement component C2 (at 37 degrees Celsius) KM=1.9 µM for complement component C4 (at 37 degrees Celsius)

Ontologies

Keywords
Biological process	Complement pathway Immune response Innate immunity
Coding sequence diversity	Polymorphism
Domain	EGF-like domain Repeat Signal Sushi
Ligand	Calcium Metal-binding
Molecular function	Hydrolase Protease Serine protease
PTM	Disulfide bond Glycoprotein Hydroxylation
Technical term	3D-structure Complete proteome Direct protein sequencing
Gene Ontology (GO)
Biological process	complement activation, classical pathway Inferred from electronic annotation. Source: UniProtKB-KW innate immune response Inferred from electronic annotation. Source: UniProtKB-KW proteolysis Inferred from electronic annotation. Source: InterPro
Cellular component	extracellular region Inferred from Experiment. Source: Reactome
Molecular function	calcium ion binding Inferred from electronic annotation. Source: UniProtKB-KW serine-type endopeptidase activity Ref.13 Inferred from direct assay. Source: UniProtKB
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Signal peptide

1 – 15

15

Ref.7

Chain

16 – 688

673

Complement C1s subcomponent

PRO_0000027586

Chain

16 – 437

422

Complement C1s subcomponent heavy chain

PRO_0000027587

Chain

438 – 688

251

Complement C1s subcomponent light chain

PRO_0000027588

Regions

Domain

16 – 130

115

CUB 1

Domain

131 – 172

42

EGF-like; calcium-binding

Domain

175 – 290

116

CUB 2

Domain

292 – 356

65

Sushi 1

Domain

357 – 423

67

Sushi 2

Domain

438 – 680

243

Peptidase S1

Sites

Active site

475

1

Charge relay system

Active site

529

1

Charge relay system

Active site

632

1

Charge relay system

Metal binding

60

1

Calcium

Metal binding

68

1

Calcium

Metal binding

113

1

Calcium

Metal binding

131

1

Calcium

Metal binding

132

1

Calcium; via carbonyl oxygen

Metal binding

134

1

Calcium

Metal binding

149

1

Calcium

Metal binding

150

1

Calcium; via carbonyl oxygen

Metal binding

153

1

Calcium; via carbonyl oxygen

Amino acid modifications

Modified residue

149

1

(3R)-3-hydroxyasparagine

Glycosylation

174

1

N-linked (GlcNAc...) Ref.9 Ref.16

Glycosylation

406

1

N-linked (GlcNAc...) Ref.16 Ref.15 Ref.18

Disulfide bond

65 ↔ 83

Ref.11

Disulfide bond

135 ↔ 147

Ref.11

Disulfide bond

143 ↔ 156

Ref.11

Disulfide bond

158 ↔ 171

Ref.11

Disulfide bond

175 ↔ 202

Ref.11

Disulfide bond

234 ↔ 251

Ref.11

Disulfide bond

294 ↔ 341

Ref.11

Disulfide bond

321 ↔ 354

Ref.11

Disulfide bond

359 ↔ 403

Ref.11

Disulfide bond

386 ↔ 421

Ref.11

Disulfide bond

425 ↔ 549

Interchain (between heavy and light chains) Ref.11

Disulfide bond

595 ↔ 618

Ref.11

Disulfide bond

628 ↔ 659

Ref.11

Natural variations

Natural variant

119

1

R → H: dbSNP rs12146727.

VAR_033643

Natural variant

327

1

V → L: dbSNP rs2239170.

VAR_033644

Natural variant

383

1

R → H: dbSNP rs20573.

VAR_014565

Experimental info

Sequence conflict

294

1

C → K AA sequence Ref.7

Sequence conflict

513

1

G → GG Ref.6

Sequence conflict

573

1

T → A AA sequence Ref.8

Sequence conflict

645 – 646

2

TK → GR AA sequence Ref.8

Secondary structure

1

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688

Helix Strand Turn

Details...

Beta strand

19 – 24

6

Turn

26 – 29

4

Beta strand

34 – 43

10

Beta strand

48 – 58

11

Helix

63 – 65

3

Beta strand

67 – 73

7

Beta strand

80 – 82

3

Beta strand

84 – 86

3

Beta strand

96 – 112

17

Beta strand

122 – 131

10

Turn

134 – 136

3

Beta strand

143 – 150

8

Beta strand

153 – 157

5

Beta strand

368 – 370

3

Beta strand

381 – 386

6

Turn

388 – 390

3

Beta strand

391 – 393

3

Beta strand

399 – 403

5

Beta strand

409 – 411

3

Turn

412 – 414

3

Beta strand

421 – 423

3

Helix

446 – 448

3

Beta strand

452 – 455

4

Turn

456 – 459

4

Beta strand

460 – 466

7

Beta strand

469 – 472

4

Helix

474 – 477

4

Beta strand

505 – 510

6

Beta strand

531 – 537

7

Helix

555 – 557

3

Beta strand

564 – 570

7

Beta strand

583 – 590

8

Helix

592 – 596

5

Beta strand

616 – 620

5

Beta strand

635 – 639

5

Beta strand

647 – 655

9

Beta strand

661 – 667

7

Helix

668 – 671

4

Helix

672 – 681

10

Sequences

	Sequence		Length	Mass (Da)
	P09871-1 [UniParc]. Last modified July 1, 1989. Version 1. Checksum: 85522647A4C47205	FASTA	688	76,684
	10 20 30 40 50 60 MWCIVLFSLL AWVYAEPTMY GEILSPNYPQ AYPSEVEKSW DIEVPEGYGI HLYFTHLDIE 70 80 90 100 110 120 LSENCAYDSV QIISGDTEEG RLCGQRSSNN PHSPIVEEFQ VPYNKLQVIF KSDFSNEERF 130 140 150 160 170 180 TGFAAYYVAT DINECTDFVD VPCSHFCNNF IGGYFCSCPP EYFLHDDMKN CGVNCSGDVF 190 200 210 220 230 240 TALIGEIASP NYPKPYPENS RCEYQIRLEK GFQVVVTLRR EDFDVEAADS AGNCLDSLVF 250 260 270 280 290 300 VAGDRQFGPY CGHGFPGPLN IETKSNALDI IFQTDLTGQK KGWKLRYHGD PMPCPKEDTP 310 320 330 340 350 360 NSVWEPAKAK YVFRDVVQIT CLDGFEVVEG RVGATSFYST CQSNGKWSNS KLKCQPVDCG 370 380 390 400 410 420 IPESIENGKV EDPESTLFGS VIRYTCEEPY YYMENGGGGE YHCAGNGSWV NEVLGPELPK 430 440 450 460 470 480 CVPVCGVPRE PFEEKQRIIG GSDADIKNFP WQVFFDNPWA GGALINEYWV LTAAHVVEGN 490 500 510 520 530 540 REPTMYVGST SVQTSRLAKS KMLTPEHVFI HPGWKLLEVP EGRTNFDNDI ALVRLKDPVK 550 560 570 580 590 600 MGPTVSPICL PGTSSDYNLM DGDLGLISGW GRTEKRDRAV RLKAARLPVA PLRKCKEVKV 610 620 630 640 650 660 EKPTADAEAY VFTPNMICAG GEKGMDSCKG DSGGAFAVQD PNDKTKFYAA GLVSWGPQCG 670 680 TYGLYTRVKN YVDWIMKTMQ ENSTPRED

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Molecular cloning of cDNA for human complement component C1s. The complete amino acid sequence." McKinnon C.M., Carter P.E., Smyth S.J., Dunbar B., Fothergill J.E. Eur. J. Biochem. 169:547-553(1987) [PubMed: 3500856] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Tissue: Liver.
[2]	"Complete cDNA sequence of human complement Cls and close physical linkage of the homologous genes Cls and Clr." Tosi M., Duponchel C., Meo T., Julier C. Biochemistry 26:8516-8524(1987) [PubMed: 2831944] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA].
[3]	"Human genes for complement components C1r and C1s in a close tail-to-tail arrangement." Kusumoto H., Hirosawa S., Salier J.-P., Hagen F.S., Kurachi K. Proc. Natl. Acad. Sci. U.S.A. 85:7307-7311(1988) [PubMed: 2459702] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA].
[4]	"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)." The MGC Project Team Genome Res. 14:2121-2127(2004) [PubMed: 15489334] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. Tissue: PNS.
[5]	"Two lineages of mannose-binding lectin-associated serine protease (MASP) in vertebrates." Endo Y., Takahashi M., Nakao M., Saiga H., Sekine H., Matsushita M., Nonaka M., Fujita T. J. Immunol. 161:4924-4930(1998) [PubMed: 9794427] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-329. Tissue: Peripheral blood leukocyte.
[6]	"Complement genes C1r and C1s feature an intronless serine protease domain closely related to haptoglobin." Tosi M., Duponchel C., Meo T., Couture-Tosi E. J. Mol. Biol. 208:709-714(1989) [PubMed: 2553984] [Abstract] Cited for: NUCLEOTIDE SEQUENCE OF 291-688.
[7]	"Human complement component C1s. Partial sequence determination of the heavy chain and identification of the peptide bond cleaved during activation." Spycher S.E., Nick H., Rickli E.E. Eur. J. Biochem. 156:49-57(1986) [PubMed: 3007145] [Abstract] Cited for: PROTEIN SEQUENCE OF 16-61; 168-219; 287-334 AND 384-445.
[8]	"The serine proteinase chain of human complement component C1s. Cyanogen bromide cleavage and N-terminal sequences of the fragments." Carter P.E., Dunbar B., Fothergill J.E. Biochem. J. 215:565-571(1983) [PubMed: 6362661] [Abstract] Cited for: PROTEIN SEQUENCE OF 438-500; 503-534; 542-601; 617-623 AND 626-656.
[9]	"Chemical and functional characterization of a fragment of C1-s containing the epidermal growth factor homology region." Thielens N.M., van Dorsselaer A., Gagnon J., Arlaud G.J. Biochemistry 29:3570-3578(1990) [PubMed: 2141278] [Abstract] Cited for: PARTIAL PROTEIN SEQUENCE, GLYCOSYLATION AT ASN-174, HYDROXYLATION AT ASN-149.
[10]	"Effect of lactoperoxidase-catalyzed iodination on the Ca(2+)-dependent interactions of human C1s. Location of the iodination sites." Illy C., Thielens N.M., Gagnon J., Arlaud G.J. Biochemistry 30:7135-7141(1991) [PubMed: 1854725] [Abstract] Cited for: PARTIAL PROTEIN SEQUENCE. Tissue: Plasma.
[11]	"Identification of the disulfide bonds of human complement C1s." Hess D., Schaller J., Rickli E.E. Biochemistry 30:2827-2833(1991) [PubMed: 2007122] [Abstract] Cited for: DISULFIDE BONDS.
[12]	"Structure of the catalytic region of human complement protease C1s: study by chemical cross-linking and three-dimensional homology modeling." Rossi V., Gaboriaud C., Lacroix M., Ulrich J., Fontecilla-Camps J.-C., Gagnon J., Arlaud G.J. Biochemistry 34:7311-7321(1995) [PubMed: 7779774] [Abstract] Cited for: PARTIAL PROTEIN SEQUENCE, 3D-STRUCTURE MODELING OF CATALYTIC DOMAIN.
[13]	"Substrate specificities of recombinant mannan-binding lectin-associated serine proteases-1 and -2." Rossi V., Cseh S., Bally I., Thielens N.M., Jensenius J.C., Arlaud G.J. J. Biol. Chem. 276:40880-40887(2001) [PubMed: 11527969] [Abstract] Cited for: CATALYTIC ACTIVITY, BIOPHYSICOCHEMICAL PROPERTIES, ENZYME REGULATION.
[14]	"Molecular basis of a selective C1s deficiency associated with early onset multiple autoimmune diseases." Dragon-Durey M.-A., Quartier P., Fremeaux-Bacchi V., Blouin J., de Barace C., Prieur A.-M., Weiss L., Fridman W.-H. J. Immunol. 166:7612-7616(2001) [PubMed: 11390518] [Abstract] Cited for: DISEASE.
[15]	"Human plasma N-glycoproteome analysis by immunoaffinity subtraction, hydrazide chemistry, and mass spectrometry." Liu T., Qian W.-J., Gritsenko M.A., Camp D.G. II, Monroe M.E., Moore R.J., Smith R.D. J. Proteome Res. 4:2070-2080(2005) [PubMed: 16335952] [Abstract] Cited for: GLYCOSYLATION [LARGE SCALE ANALYSIS] AT ASN-406, MASS SPECTROMETRY. Tissue: Plasma.
[16]	"Glycoproteomics analysis of human liver tissue by combination of multiple enzyme digestion and hydrazide chemistry." Chen R., Jiang X., Sun D., Han G., Wang F., Ye M., Wang L., Zou H. J. Proteome Res. 8:651-661(2009) [PubMed: 19159218] [Abstract] Cited for: GLYCOSYLATION [LARGE SCALE ANALYSIS] AT ASN-174 AND ASN-406, MASS SPECTROMETRY. Tissue: Liver.
[17]	"Crystal structure of the catalytic domain of human complement c1s: a serine protease with a handle." Gaboriaud C., Rossi V., Bally I., Arlaud G.J., Fontecilla-Camps J.-C. EMBO J. 19:1755-1765(2000) [PubMed: 10775260] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (1.7 ANGSTROMS) OF 358-688.
[18]	"X-ray structure of the Ca2+-binding interaction domain of C1s. Insights into the assembly of the C1 complex of complement." Gregory L.A., Thielens N.M., Arlaud G.J., Fontecilla-Camps J.-C., Gaboriaud C. J. Biol. Chem. 278:32157-32164(2003) [PubMed: 12788922] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (1.5 ANGSTROMS) OF 16-174, CALCIUM-BINDING SITES, GLYCOSYLATION AT ASN-406.
+	Additional computationally mapped references.

Web resources

C1Sbase

C1S mutation db

Cross-references

Sequence databases

EMBLGenBankDDBJ

X06596 mRNA. Translation: CAA29817.1.
M18767 mRNA. Translation: AAA51853.1.
J04080 mRNA. Translation: AAA51852.1.
BC056903 mRNA. Translation: AAH56903.1.
AB009076 Genomic DNA. Translation: BAA86864.1.

IPI

IPI00017696.

PIR

C1HUS. A40496.

RefSeq

NP_001725.1.
NP_958850.1.

UniGene

Hs.458355

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1ELV	X-ray	1.70	A	358-688	[»]
1NZI	X-ray	1.50	A/B	16-174	[»]

ModBase

Search...

Protein-protein interaction databases

STRING

P09871.

Protein family/group databases

MEROPS

S01.193.

PTM databases

PhosphoSite

P09871.

2-D gel databases

SWISS-2DPAGE

P09871.

Proteomic databases

PeptideAtlas

P09871.

PRIDE

P09871.

Genome annotation databases

Ensembl

ENST00000328916; ENSP00000328173; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000360817; ENSP00000354057; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000382222; ENSP00000371657; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000402681; ENSP00000384171; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000403949; ENSP00000384464; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000406697; ENSP00000385035; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000413211; ENSP00000406643; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000423384; ENSP00000399892; ENSG00000182326; Homo sapiens. [Genome view]
ENST00000443875; ENSP00000397921; ENSG00000182326; Homo sapiens. [Genome view]

GeneID

716.

KEGG

hsa:716.

UCSC

uc001qsj.1. human.

Organism-specific databases

CTD

716.

GeneCards

GC12P007038.

H-InvDB

HIX0019128.

HGNC

HGNC:1247. C1S.

HPA

CAB016722.
HPA018852.

MIM

120580. gene+phenotype.

PharmGKB

PA25636.

GenAtlas

Search...

Phylogenomic databases

HOVERGEN

P09871.

OMA

NGSWVNE.

Enzyme and pathway databases

BRENDA

3.4.21.42. 247.

Reactome

REACT_6900. Signaling in Immune system.

Gene expression databases

ArrayExpress

P09871.

Bgee

P09871.

Genevestigator

P09871.

GermOnline

ENSG00000182326. Homo sapiens.

Family and domain databases

InterPro

IPR016060. Complement_control_module.
IPR000859. CUB.
IPR006209. EGF.
IPR013032. EGF-like_reg_CS.
IPR000152. EGF-type_Asp/Asn_hydroxyl_site.
IPR001881. EGF_Ca_bd.
IPR018097. EGF_Ca_bd_CS.
IPR018114. Peptidase_S1/S6_AS.
IPR001254. Peptidase_S1_S6.
IPR001314. Peptidase_S1A.
IPR000436. Sushi_SCR_CCP.
[Graphical view]

Gene3D

G3DSA:2.10.70.10. Complement_control_module. 1 hit.
G3DSA:2.60.120.290. CUB. 2 hits.

Pfam

PF00431. CUB. 2 hits.
PF00008. EGF. 1 hit.
PF00084. Sushi. 2 hits.
PF00089. Trypsin. 1 hit.
[Graphical view]

PRINTS

PR00722. CHYMOTRYPSIN.

SMART

SM00032. CCP. 2 hits.
SM00042. CUB. 2 hits.
SM00179. EGF_CA. 1 hit.
SM00020. Tryp_SPc. 1 hit.
[Graphical view]

PROSITE

PS00010. ASX_HYDROXYL. 1 hit.
PS01180. CUB. 2 hits.
PS00022. EGF_1. False negative.
PS01186. EGF_2. False negative.
PS50026. EGF_3. False negative.
PS01187. EGF_CA. 1 hit.
PS50923. SUSHI. 2 hits.
PS50240. TRYPSIN_DOM. 1 hit.
PS00134. TRYPSIN_HIS. False negative.
PS00135. TRYPSIN_SER. 1 hit.
[Graphical view]

ProtoNet

Search...

Other Resources

DrugBank

DB00054. Abciximab.
DB00051. Adalimumab.
DB00074. Basiliximab.
DB00002. Cetuximab.
DB00005. Etanercept.
DB00056. Gemtuzumab ozogamicin.
DB00078. Ibritumomab.
DB00028. Immune globulin.
DB00075. Muromonab.
DB00073. Rituximab.
DB00072. Trastuzumab.

NextBio

2912.

PMAP-CutDB

P09871.

SOURCE

Search...

Entry information

Entry name

C1S_HUMAN

Accession

Primary (citable) accession number: P09871
Secondary accession number(s): Q9UCU7 , Q9UCU8, Q9UCU9, Q9UCV0, Q9UCV1, Q9UCV2, Q9UCV3, Q9UCV4, Q9UCV5, Q9UM14

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 1, 1989
Last sequence update:	July 1, 1989
Last modified:	November 3, 2009
This is version 138 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HPI (Human Proteome Initiative)

Disclaimer

Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care.