Reviewed, UniProtKB/Swiss-Prot Q7SYF1 (VSPP_CERCE)

Names and origin

Protein names	Recommended name:     Cerastocytin     EC=3.4.21.74 Alternative name(s):     Proaggregant serine proteinase     CC-PPP
Organism	Cerastes cerastes (Horned desert viper)
Taxonomic identifier	8697 [NCBI]
Taxonomic lineage	Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Lepidosauria › Squamata › Scleroglossa › Serpentes › Colubroidea › Viperidae › Viperinae › Cerastes

Protein attributes

Sequence length	256 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	Thrombin-like snake venom serine protease. Is a potent inducer of platelet aggregation and hydrolyzes fibrinogen alpha-, beta- and gamma-chains. High concentrations of this enzyme also cleave prothrombin and Factor X. Ref.1 Ref.2
Catalytic activity	Selective cleavage of Arg-|-Xaa bond in fibrinogen, to form fibrin, and release fibrinopeptide A. The specificity of further degradation of fibrinogen varies with species origin of the enzyme.
Enzyme regulation	Its platelets aggregating activity is inhibited by chlorpromazine, theophylline mepacrine. Its platelet aggregating activity and its amidolytic activity are inhibited by PMSF, TPCK, TLCK and soybean trypsin inhibitors. Is unaffected by hirudin or by antithrombin III in the presence of heparin. Ref.2
Subunit structure	Monomer. Ref.2
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Sequence similarities	Belongs to the peptidase S1 family. Snake venom subfamily. Contains 1 peptidase S1 domain.
Biophysicochemical properties	Kinetic parameters: KM=309 µM for S-2238 KM=850 µM for S-2251

Ontologies

Keywords
Biological process	Blood coagulation
Cellular component	Secreted
Domain	Signal
Molecular function	Hydrolase Protease Serine protease Toxin
PTM	Disulfide bond Glycoprotein Zymogen
Technical term	Direct protein sequencing
Gene Ontology (GO)
Biological process	blood coagulation Inferred from electronic annotation. Source: UniProtKB-KW pathogenesis Inferred from electronic annotation. Source: UniProtKB-KW proteolysis Inferred from electronic annotation. Source: InterPro
Cellular component	extracellular region Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular function	serine-type endopeptidase activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Signal peptide	1 – 18	18	Potential
	Propeptide	19 – 24	6	Ref.2		PRO_0000294994
	Chain	25 – 256	232	Cerastocytin		PRO_0000294995
Regions
	Domain	25 – 247	223	Peptidase S1
Sites
	Active site	65	1	Charge relay system By similarity
	Active site	108	1	Charge relay system By similarity
	Active site	202	1	Charge relay system By similarity
Amino acid modifications
	Glycosylation	44	1	N-linked (GlcNAc...) Potential
	Glycosylation	119	1	N-linked (GlcNAc...) Potential
	Glycosylation	120	1	N-linked (GlcNAc...) Potential
	Glycosylation	152	1	N-linked (GlcNAc...) Potential
	Disulfide bond	31 ↔ 161		By similarity
	Disulfide bond	98 ↔ 254		By similarity
	Disulfide bond	140 ↔ 208		By similarity
	Disulfide bond	172 ↔ 187		By similarity
	Disulfide bond	198 ↔ 223		By similarity
Experimental info
	Sequence conflict	44	1	N → T AA sequence Ref.2

Sequences

	Sequence		Length	Mass (Da)
	Q7SYF1-1 [UniParc]. Last modified October 1, 2003. Version 1. Checksum: 62F57976F89ECED1	FASTA	256	27,974
	10 20 30 40 50 60 MVLISVLASL LVLQLSYAQK SSELVIGGAE CNINEHRSLV LLYNSSRLFG GGTLINKEWV 70 80 90 100 110 120 LSAAHCDGEN MKIYLGLHHF RLPNKDRQIR VAKEKYFCRD RKSIVDKDIM LIKLNKPVNN 130 140 150 160 170 180 STHIAPLSLP SSPPSVGSDC RIMGWGTITS PNDTYPKVPH CANINILEHS LCERAYNDLS 190 200 210 220 230 240 ASSRTLCAGI EKGGIDTCKG DSGGPLICNG QIQGIVSWGD EVCGKPNKPG VYTKVFDYTD 250 WIRNIIAGNT AATCPQ

References

[1]	"Molecular cloning and expression of a functional snake venom serine proteinase, with platelet aggregating activity, from the Cerastes cerastes viper." Dekhil H., Wisner A., Marrakchi N., El Ayeb M., Bon C., Karoui H. Biochemistry 42:10609-10618(2003) [PubMed: 12962484] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES. Tissue: Venom gland.
[2]	"Cerastocytin, a new thrombin-like platelet activator from the venom of the Tunisian viper Cerastes cerastes." Marrakchi N., Zingali R.B., Karoui H., Bon C., el Ayeb M. Biochim. Biophys. Acta 1244:147-156(1995) [PubMed: 7766651] [Abstract] Cited for: PROTEIN SEQUENCE OF 25-74, FUNCTION, ENZYME REGULATION, SUBUNIT. Tissue: Venom.

Cross-references

Sequence databases
EMBLGenBankDDBJ	AJ553977 mRNA. Translation: CAD86932.1.
PIR	S55674.
3D structure databases
HSSP	HSSP built from PDB template 1EZX based on UniProtKB P00760.
ModBase	Search...
Phylogenomic databases
HOVERGEN	Q7SYF1.
Enzyme and pathway databases
BRENDA	3.4.21.74. 18553.
Family and domain databases
InterPro	IPR018114. Peptidase_S1/S6_AS. IPR001254. Peptidase_S1_S6. IPR001314. Peptidase_S1A. [Graphical view]
Pfam	PF00089. Trypsin. 1 hit. [Graphical view]
PRINTS	PR00722. CHYMOTRYPSIN.
SMART	SM00020. Tryp_SPc. 1 hit. [Graphical view]
PROSITE	PS50240. TRYPSIN_DOM. 1 hit. PS00134. TRYPSIN_HIS. 1 hit. PS00135. TRYPSIN_SER. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

VSPP_CERCE

Accession

Primary (citable) accession number: Q7SYF1
Secondary accession number(s): Q9PRT4

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 10, 2007
Last sequence update:	October 1, 2003
Last modified:	June 16, 2009
This is version 37 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

Tox-Prot (Toxin Annotation Project)