ID   VSP4A_CERCE             Reviewed;          15 AA.
AC   Q7LZF4;
DT   10-JUL-2007, integrated into UniProtKB/Swiss-Prot.
DT   15-DEC-2003, sequence version 1.
DT   03-AUG-2022, entry version 43.
DE   RecName: Full=Snake venom serine protease IVa;
DE            Short=SVSP;
DE            EC=3.4.21.-;
DE   AltName: Full=Basic proteinase IVa;
DE   Flags: Fragment;
OS   Cerastes cerastes (Horned desert viper).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Viperinae; Cerastes.
OX   NCBI_TaxID=8697;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, ACTIVITY REGULATION, AND SUBUNIT.
RC   TISSUE=Venom;
RX   PubMed=7612660; DOI=10.1016/0167-4838(95)00050-5;
RA   Basheer A.R., el-Asmar M.F., Soslau G.;
RT   "Characterization of a potent platelet aggregation inducer from Cerastes
RT   cerastes (Egyptian sand viper) venom.";
RL   Biochim. Biophys. Acta 1250:97-109(1995).
CC   -!- FUNCTION: Snake venom serine protease that potently induces platelet
CC       aggregation. Its aggregatory activity is partially inhibited by
CC       monoclonal antibodies against GPIb and the thrombin receptor. Its
CC       ability to induce intracellular Ca(2+) release is blocked by
CC       pretreating platelets with thrombin. Hydrolyzes thrombin chromogenic
CC       substrate CBS 34.47, but shows very weak coagulant activity. Can
CC       hydrolyze fibrinogen alpha-chains. {ECO:0000269|PubMed:7612660}.
CC   -!- ACTIVITY REGULATION: Inactivated by p-APMSF, leupeptin, iodoacetamide,
CC       protein kinase C inhibitor, phosphatase inhibitor, ATP and PGE1. Is
CC       insensitive to acetylsalicylic acid, ADP scavenger system, protein
CC       kinase A inhibitor and hirudin. {ECO:0000269|PubMed:7612660}.
CC   -!- SUBUNIT: Dimer (it is unsure whether homo- or heterodimer).
CC       {ECO:0000269|PubMed:7612660}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- SIMILARITY: Belongs to the peptidase S1 family. Snake venom subfamily.
CC       {ECO:0000255|PROSITE-ProRule:PRU00274}.
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DR   PIR; S57201; S57201.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0008236; F:serine-type peptidase activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0006508; P:proteolysis; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Hemostasis impairing toxin; Hydrolase;
KW   Platelet aggregation activating toxin; Protease; Secreted; Serine protease;
KW   Toxin.
FT   CHAIN           1..>15
FT                   /note="Snake venom serine protease IVa"
FT                   /id="PRO_0000294992"
FT   DOMAIN          1..>15
FT                   /note="Peptidase S1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   NON_TER         15
SQ   SEQUENCE   15 AA;  1638 MW;  0471E55327D52FDA CRC64;
     VIGGAEENIN EHRSL