ID   SPI1_CRAVI              Reviewed;          90 AA.
AC   Q30HU9; P84574;
DT   07-FEB-2006, integrated into UniProtKB/Swiss-Prot.
DT   06-DEC-2005, sequence version 1.
DT   03-AUG-2022, entry version 21.
DE   RecName: Full=Serine protease inhibitor Cvsi-1;
DE   Flags: Precursor;
OS   Crassostrea virginica (Eastern oyster).
OC   Eukaryota; Metazoa; Spiralia; Lophotrochozoa; Mollusca; Bivalvia;
OC   Autobranchia; Pteriomorphia; Ostreida; Ostreoidea; Ostreidae; Crassostrea.
OX   NCBI_TaxID=6565;
RN   [1] {ECO:0000305, ECO:0000312|EMBL:AAZ41364.1}
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 20-90, FUNCTION,
RP   SUBCELLULAR LOCATION, TISSUE SPECIFICITY, MASS SPECTROMETRY, AND DISULFIDE
RP   BONDS.
RC   TISSUE=Digestive gland {ECO:0000269|PubMed:16872855}, and
RC   Hemolymph {ECO:0000269|PubMed:16872855};
RX   PubMed=16872855; DOI=10.1016/j.cbpb.2006.05.010;
RA   Xue Q.-G., Waldrop G.L., Schey K.L., Itoh N., Ogawa M., Cooper R.K.,
RA   Losso J.N., La Peyre J.F.;
RT   "A novel slow-tight binding serine protease inhibitor from eastern oyster
RT   (Crassostrea virginica) plasma inhibits perkinsin, the major extracellular
RT   protease of the oyster protozoan parasite Perkinsus marinus.";
RL   Comp. Biochem. Physiol. 145B:16-26(2006).
RN   [2]
RP   FUNCTION, AND TISSUE SPECIFICITY.
RX   PubMed=19720077; DOI=10.1016/j.dci.2009.08.007;
RA   La Peyre J.F., Xue Q.G., Itoh N., Li Y., Cooper R.K.;
RT   "Serine protease inhibitor cvSI-1 potential role in the eastern oyster host
RT   defense against the protozoan parasite Perkinsus marinus.";
RL   Dev. Comp. Immunol. 34:84-92(2010).
CC   -!- FUNCTION: Slow-binding inhibitor of serine proteases. The inhibitor
CC       rapidly binds to the protease forming a weak enzyme-inhibitor complex,
CC       and this is followed by a slow isomerization forming a tight-binding
CC       enzyme-inhibitor complex. Active against subtilisin A, perkinsin and
CC       trypsin with dissociation constants of 0.29 nM, 13.7 nM and 17.7 nM
CC       respectively. Not active against thermolysin, papain or pepsin. Has
CC       antiparasitic activity against the protozoan P.marinus.
CC       {ECO:0000269|PubMed:16872855, ECO:0000269|PubMed:19720077}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:16872855}.
CC   -!- TISSUE SPECIFICITY: Detected in hemolymph (at protein level). In
CC       oysters collected in the summer the expression level is highest in the
CC       digestive gland with low levels of expression in gill, mantle, labial
CC       palp, style-sac midgut, gonad, heart, and hemocyte. In winter
CC       expression levels are higher in all tissues with highest expression
CC       levels observed in the digestive gland. Within the digestive gland
CC       expression is limited to the basophil cells of the digestive
CC       diverticula. {ECO:0000269|PubMed:16872855,
CC       ECO:0000269|PubMed:19720077}.
CC   -!- PTM: Contains 6 disulfide bonds. {ECO:0000305}.
CC   -!- MASS SPECTROMETRY: Mass=7609.6; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:16872855};
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DR   EMBL; DQ092546; AAZ41364.1; -; mRNA.
DR   AlphaFoldDB; Q30HU9; -.
DR   MEROPS; I84.002; -.
DR   Proteomes; UP000694844; Genome assembly.
DR   GO; GO:0005615; C:extracellular space; IDA:UniProtKB.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IDA:UniProtKB.
PE   1: Evidence at protein level;
KW   Antimicrobial; Direct protein sequencing; Disulfide bond;
KW   Protease inhibitor; Reference proteome; Secreted;
KW   Serine protease inhibitor; Signal.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000269|PubMed:16872855"
FT   CHAIN           20..90
FT                   /note="Serine protease inhibitor Cvsi-1"
FT                   /evidence="ECO:0000269|PubMed:16872855"
FT                   /id="PRO_0000046060"
SQ   SEQUENCE   90 AA;  9715 MW;  957357DD4AC04FEE CRC64;
     MDVVRTLILC VCLFGLTFAV PCIDGVCTSN ELQCASGYVK GCHAGLCTCE HATTQSCTVV
     NNCLHLGTCS LHGRDGFWHC VDSVCKCFFF