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PR00293

Identifier
SQUASHINHBTR  [View Relations]  [View Alignment]  
Accession
PR00293
No. of Motifs
2
Creation Date
25-JAN-1995  (UPDATE 18-JUN-1999)
Title
Squash serine protease inhibitor signature
Database References

PROSITE; PS00286 SQUASH_INHIBITOR
BLOCKS; BL00286
PFAM; PF00299 squash
INTERPRO; IPR000737
PDB; 1CTI
SCOP; 1CTI
Literature References
1. BODE, W., GREYLING, H.J., HUBER, R., OTLEWSKI, J. AND WILUSZ, T.
The refined 2.0 A X-ray crystal structure of the complex formed between 
bovine beta-trypsin and CMTI-I, a trypsin inhibitor from squash seeds
with the carboxypeptidase A inhibitor from potatoes.
FEBS LETT. 242 285-292 (1989).
 
2. KRISHNAMOORTHI, R., GONG, Y.X., LIN, C.L. AND VANDERVELDE, D.
Two-dimensional NMR studies of squash family inhibitors. Sequence-specific
proton assignments and secondary structure of reactive-site hydrolyzed 
Cucurbita maxima trypsin inhibitor III.
BIOCHEMISTRY 31 898-904 (1992).

Documentation
The squash inhibitors form one of a number of serine protease inhibitor
families. The proteins (found in the seeds of squash, cucumber, balsam
pear, etc.) are approximately 30 residues in length and contain 6 Cys
residues, which form 3 disulphide bonds [1]. The inhibitors function by
being taken up by a serine protease (such as trypsin), which cleaves the
peptide bond between Arg/Lys and Ile residues in the N-terminal portion of
the protein [1,2]. 
 
Structural studies have shown that the inhibitor has an ellipsoidal shape,
and is largely composed of beta-turns [1]. The fold and Cys connectivity of
the proteins resembles that of potato carboxypeptidase A inhibitor [2].
 
SQUASHINHBTR is a 2-element fingerprint that provides a signature for
squash serine protease inhibitors. The fingerprint was derived from an
initial alignment of 7 sequences: the motifs span the region encoded by
PROSITE pattern SQUASH_INHIBITOR (PS00286), which contains the active bond
and 5 conserved cysteines. Two iterations on OWL25.1 were required to 
reach convergence, at which point a true set comprising 26 sequences was
identified. 
 
An update on SPTR37_9f identified a true set of 20 sequences.
Summary Information
20 codes involving  2 elements
Composite Feature Index
22020
12
True Positives
IEL1_MOMCH    ITI1_LAGLE    ITR1_CITVU    ITR1_CUCMA    
ITR1_LUFCY ITR1_MOMCH ITR1_MOMRE ITR2_BRYDI
ITR2_CUCSA ITR2_ECBEL ITR2_LUFCY ITR2_MOMCH
ITR3_CUCMC ITR3_CUCPE ITR3_LUFCY ITR4_CUCMA
ITR4_CUCSA ITR4_LUFCY ITRA_MOMCH Q43667
Sequence Titles
IEL1_MOMCH  ELASTASE INHIBITOR I (MCEI-I) - MOMORDICA CHARANTIA (BITTER GOURD) (BALSAM PEAR). 
ITI1_LAGLE TRYPSIN INHIBITORS I, II, AND III (LLDTI-I OR LLDTI-II OR LLTI-III) - LAGENARIA LEUCANTHA (BOTTLE GOURD) (LAGENARIA SICERARIA).
ITR1_CITVU TRYPSIN INHIBITOR I (CVTI-I) - CITRULLUS VULGARIS (WATERMELON).
ITR1_CUCMA TRYPSIN INHIBITOR I (CMTI-I) - CUCURBITA MAXIMA (PUMPKIN) (WINTER SQUASH).
ITR1_LUFCY TRYPSIN INHIBITOR I (LCTI-I) - LUFFA CYLINDRICA (SMOOTH LOOFAH) (SPONGE GOURD).
ITR1_MOMCH TRYPSIN INHIBITOR I (MCTI-I) - MOMORDICA CHARANTIA (BITTER GOURD) (BALSAM PEAR).
ITR1_MOMRE TRYPSIN INHIBITOR I (MRTI-I) - MOMORDICA REPENS.
ITR2_BRYDI TRYPSIN INHIBITOR II (BDTI-II) - BRYONIA DIOICA (RED BRYONY).
ITR2_CUCSA TRYPSIN INHIBITOR IIB (CSTI-IIB) - CUCUMIS SATIVUS (CUCUMBER).
ITR2_ECBEL TRYPSIN INHIBITOR II (EETI-II) - ECBALLIUM ELATERIUM (JUMPING CUCUMBER).
ITR2_LUFCY TRYPSIN INHIBITOR II (LCTI-II) - LUFFA CYLINDRICA (SMOOTH LOOFAH) (SPONGE GOURD).
ITR2_MOMCH TRYPSIN INHIBITOR II (MCTI-II) (MCTI-A) - MOMORDICA CHARANTIA (BITTER GOURD) (BALSAM PEAR).
ITR3_CUCMC TRYPSIN INHIBITORS I, II AND III (CMCTI-I, CMCT-II AND CMCTI-III) - CUCUMIS MELO VAR. CONOMON (ORIENTAL PICKLING MELON).
ITR3_CUCPE TRYPSIN INHIBITORS III AND II (CPTI-III AND CPTI-II) - CUCURBITA PEPO (VEGETABLE MARROW) (SUMMER SQUASH).
ITR3_LUFCY TRYPSIN INHIBITOR I (TGTI-I) - LUFFA CYLINDRICA (SMOOTH LOOFAH) (SPONGE GOURD).
ITR4_CUCMA TRYPSIN INHIBITORS IV AND III (CMTI-IV AND CMTI-III) - CUCURBITA MAXIMA (PUMPKIN) (WINTER SQUASH).
ITR4_CUCSA TRYPSIN INHIBITOR IV (CSTI-IV) - CUCUMIS SATIVUS (CUCUMBER).
ITR4_LUFCY TRYPSIN INHIBITOR II PRECURSOR (TGT-II) - LUFFA CYLINDRICA (SMOOTH LOOFAH) (SPONGE GOURD).
ITRA_MOMCH TRYPSIN INHIBITOR A - MOMORDICA CHARANTIA (BITTER GOURD) (BALSAM PEAR).
Q43667 TRICHOSANTHES TRYPSIN INHIBITOR-I - TRICHOSANTHES KIRILOWII (MONGOLIAN SNAKE-GOURD).
Scan History
OWL25_1    2  100  NSINGLE    
SPTR37_9f 3 25 NSINGLE
Initial Motifs
Motif 1  width=10
Element Seqn Id St Int Rpt
CPRILMECKK NRL_1CTI 3 3 -
CPRILMECKR ITR1_MOMRE 3 3 -
CPRILMKCKK ITR4_CUCMA 6 6 -
CPRILMRCKR ITR2_BRYDI 3 3 -
CPRILMRCKQ ITR2_ECBEL 2 2 -
CPKILMECKK ITR3_CUCPE 6 6 -
CPLIWMECKR IEL1_MOMCH 3 3 -

Motif 2 width=10
Element Seqn Id St Int Rpt
DSDCLAQCIC IEL1_MOMCH 13 0 -
DSDCLAECVC NRL_1CTI 13 0 -
DSDCLAQCVC ITR1_MOMRE 13 0 -
DSDCLAECVC ITR4_CUCMA 16 0 -
DSDCLAGCVC ITR2_BRYDI 13 0 -
DSDCLAGCVC ITR2_ECBEL 12 0 -
DSDCLAECIC ITR3_CUCPE 16 0 -
Final Motifs
Motif 1  width=10
Element Seqn Id St Int Rpt
CPRILMECKK ITR1_CUCMA 3 3 -
CPRILMECKR ITR1_MOMRE 3 3 -
CPRILMKCKK ITR4_CUCMA 6 6 -
CPRILMRCKR ITR2_BRYDI 3 3 -
CPRILMRCKQ ITR2_ECBEL 2 2 -
CPRIYMECKH ITI1_LAGLE 4 4 -
CPKILMECKK ITR3_CUCPE 6 6 -
CPRILMECSS ITR2_LUFCY 3 3 -
CPRILMECSS ITR1_LUFCY 3 3 -
CPRILMKCKH ITR4_CUCSA 3 3 -
CPRILMPCSS ITR3_LUFCY 2 2 -
CPRIYMECKR ITR1_CITVU 4 4 -
CPRIWMECKR ITR2_MOMCH 3 3 -
CPLIWMECKR IEL1_MOMCH 3 3 -
CPKILMKCKH ITR2_CUCSA 3 3 -
CPKILMKCKQ ITR3_CUCMC 4 4 -
CPRIWMECTR ITRA_MOMCH 3 3 -
CPRILKQCKR ITR1_MOMCH 4 4 -
CPRILMPCKT ITR4_LUFCY 37 37 -
CPRILMPCKV Q43667 39 39 -

Motif 2 width=10
Element Seqn Id St Int Rpt
DSDCLAECVC ITR1_CUCMA 13 0 -
DSDCLAQCVC ITR1_MOMRE 13 0 -
DSDCLAECVC ITR4_CUCMA 16 0 -
DSDCLAGCVC ITR2_BRYDI 13 0 -
DSDCLAGCVC ITR2_ECBEL 12 0 -
DSDCLADCVC ITI1_LAGLE 14 0 -
DSDCLAECIC ITR3_CUCPE 16 0 -
DSDCLAECIC ITR2_LUFCY 13 0 -
DSDCLAECIC ITR1_LUFCY 13 0 -
DSDCLPGCVC ITR4_CUCSA 13 0 -
DSDCLAECIC ITR3_LUFCY 12 0 -
DADCLADCVC ITR1_CITVU 14 0 -
DSDCMAQCIC ITR2_MOMCH 13 0 -
DSDCLAQCIC IEL1_MOMCH 13 0 -
DSDCLLDCVC ITR2_CUCSA 13 0 -
DSDCLLDCVC ITR3_CUCMC 14 0 -
DSDCMAKCIC ITRA_MOMCH 13 0 -
DSDCPGECIC ITR1_MOMCH 14 0 -
DDDCMLDCRC ITR4_LUFCY 47 0 -
NDDCLRGCKC Q43667 49 0 -