| sigcleave

## Function

Reports protein signal cleavage sites

## Description

Signal peptides mediate translocation across the ER membrane in eukaryotes. In prokaryotes signal peptides mediate translocation across the inner and outer membranes.

sigcleave predicts the site of cleavage between a signal sequence and the mature exported protein. The predictive accuracy is estimated to be around 75-80% for both prokaryotic and eukaryotic proteins.

sigcleave uses the method of von Heijne as modified by von Heijne in his later book where treatment of positions -1 and -3 in the matrix is slightly altered (see references).

### Why isn't there a cutoff to eliminate internal sites?

The program predicts cleavage sites inside the whole protein. Apart from the N-terminal sites, the other sites are not biologically relevant. Why isn't there a cutoff to eliminate internal sites?

The answer is partly because these sites can be relevant in some biological cases (additional pre-processing for example), but mostly because ...

There is one thing in bioinformatics you can not be certain of ... the start of a protein sequence. The end is easy to predict. The start depends on promoters, transcriptional controls, splicing, etc.

Most importantly, sigcleave is not perfect - you should check the results and decide whether you like the prediction.

Also, remember you can put -send 50 on the command line to make sure it only checks the first 50 residues.

## Usage

Here is a sample session with sigcleave

    % sigcleave
    Reports protein signal cleavage sites
    Input sequence(s): tsw:ach2_drome
    Minimum weight [3.5]:
    Output report [ach2_drome.sig]:

Go to the input files for this example
Go to the output files for this example

## Command line arguments

       Standard (Mandatory) qualifiers:
      [-sequence]          seqall     Sequence database USA
       -minweight          float      Minimum scoring weight value for the
                                      predicted cleavage site
      [-outfile]           report     Output report file name

       Additional (Optional) qualifiers:
       -prokaryote         boolean    Specifies the sequence is prokaryotic and
                                      changes the default scoring data file name

       Advanced (Unprompted) qualifiers: (none)
       Associated qualifiers:

       "-sequence" associated qualifiers
       -sbegin1             integer    Start of each sequence to be used
       -send1               integer    End of each sequence to be used
       -sreverse1           boolean    Reverse (if DNA)
       -sask1               boolean    Ask for begin/end/reverse
       -snucleotide1        boolean    Sequence is nucleotide
       -sprotein1           boolean    Sequence is protein
       -slower1             boolean    Make lower case
       -supper1             boolean    Make upper case
       -sformat1            string     Input sequence format
       -sdbname1            string     Database name
       -sid1                string     Entryname
       -ufo1                string     UFO features
       -fformat1            string     Features format
       -fopenfile1          string     Features file name

       "-outfile" associated qualifiers
       -rformat2            string     Report format
       -rname2              string     Base file name
       -rextension2         string     File name extension
       -rdirectory2         string     Output directory
       -raccshow2           boolean    Show accession number in the report
       -rdesshow2           boolean    Show description in the report
       -rscoreshow2         boolean    Show the score in the report
       -rusashow2           boolean    Show the full USA in the report

       General qualifiers:
       -auto                boolean    Turn off prompts
       -stdout              boolean    Write standard output
       -filter              boolean    Read standard input, write standard output
       -options             boolean    Prompt for standard and additional values
       -debug               boolean    Write debug output to program.dbg
       -verbose             boolean    Report some/full command line options
       -help                boolean    Report command line options. More
                                      information on associated and general
                                      qualifiers can be found with -help -verbose
       -warning             boolean    Report warnings
       -error               boolean    Report errors
       -fatal               boolean    Report fatal errors
       -die                 boolean    Report deaths

Standard (Mandatory) qualifiers | Allowed values | Default
--- | --- | ---
[-sequence] (Parameter 1) | Sequence database USA | Readable sequence(s) | Required
-minweight | Minimum scoring weight value for the predicted cleavage site | Number from 0.000 to 100.000 | 3.5
[-outfile] (Parameter 2) | Output report file name | Report output file |
Additional (Optional) qualifiers | Allowed values | Default
-prokaryote | Specifies the sequence is prokaryotic and changes the default scoring data file name | Boolean value Yes/No | No
Advanced (Unprompted) qualifiers | Allowed values | Default
(none)

## Input file format

sigcleave reads one or more protein sequence USAs.

### Input files for usage example

'tsw:ach2_drome' is a sequence entry in the example protein database 'tsw'

### Database entry: tsw:ach2_drome

    ID   ACH2_DROME     STANDARD;      PRT;   576 AA.
    AC   P17644;
    DT   01-AUG-1990 (REL. 15, CREATED)
    DT   01-AUG-1990 (REL. 15, LAST SEQUENCE UPDATE)
    DT   01-NOV-1997 (REL. 35, LAST ANNOTATION UPDATE)
    DE   ACETYLCHOLINE RECEPTOR PROTEIN, ALPHA-LIKE CHAIN 2 PRECURSOR.
    GN   ACRE OR SAD OR ACR96AB.
    OS   DROSOPHILA MELANOGASTER (FRUIT FLY).
    OC   EUKARYOTA; METAZOA; ARTHROPODA; TRACHEATA; HEXAPODA; INSECTA;
    OC   PTERYGOTA; DIPTERA; BRACHYCERA; MUSCOMORPHA; EPHYDROIDEA;
    OC   DROSOPHILIDAE; DROSOPHILA.
    RN   [1]
    RP   SEQUENCE FROM N.A.
    RC   TISSUE=HEAD;
    RX   MEDLINE; 90301489.
    RA   BAUMANN A., JONAS P., GUNDELFINGER E.D.;
    RT   "Sequence of D alpha 2, a novel alpha-like subunit of Drosophila
    RT   nicotinic acetylcholine receptors.";
    RL   NUCLEIC ACIDS RES. 18:3640-3640(1990).
    RN   [2]
    RP   SEQUENCE FROM N.A.
    RC   TISSUE=HEAD;
    RX   MEDLINE; 90353591.
    RA   JONAS P., BAUMANN A., MERZ B., GUNDELFINGER E.D.;
    RT   "Structure and developmental expression of the D alpha 2 gene
    RT   encoding a novel nicotinic acetylcholine receptor protein of
    RT   Drosophila melanogaster.";
    RL   FEBS LETT. 269:264-268(1990).
    RN   [3]
    RP   SEQUENCE FROM N.A.
    RX   MEDLINE; 90360975.
    RA   SAWRUK E., SCHLOSS P., BETZ H., SCHMITT B.;
    RT   "Heterogeneity of Drosophila nicotinic acetylcholine receptors: SAD,
    RT   a novel developmentally regulated alpha-subunit.";
    RL   EMBO J. 9:2671-2677(1990).
    CC   -!- FUNCTION: AFTER BINDING ACETYLCHOLINE, THE ACHR RESPONDS BY AN
    CC       EXTENSIVE CHANGE IN CONFORMATION THAT AFFECTS ALL SUBUNITS AND
    CC       LEADS TO OPENING OF AN ION-CONDUCTING CHANNEL ACROSS THE PLASMA
    CC       MEMBRANE.
    CC   -!- SUBCELLULAR LOCATION: INTEGRAL MEMBRANE PROTEIN.
    CC   -!- TISSUE SPECIFICITY: CNS IN EMBRYOS.
    CC   -!- DEVELOPMENTAL STAGE: LATE EMBRYONIC AND LATE PUPAL STAGES.
    CC   -!- SIMILARITY: BELONGS TO THE LIGAND-GATED IONIC CHANNELS FAMILY.
    CC   --------------------------------------------------------------------------
    CC   This SWISS-PROT entry is copyright. It is produced through a collaboration
    CC   between  the Swiss Institute of Bioinformatics  and the  EMBL outstation -
    CC   the European Bioinformatics Institute.  There are no  restrictions on  its
    CC   use  by  non-profit  institutions as long  as its content  is  in  no  way
    CC   modified and this statement is not removed.  Usage  by  and for commercial
    CC   entities requires a license agreement (See http://www.isb-sib.ch/announce/
    CC   or send an email to license@isb-sib.ch).
    CC   --------------------------------------------------------------------------
    DR   EMBL; X52274; G7803; -.
    DR   EMBL; X53583; G8533; -.
    DR   PIR; S11679; ACFFA2.
    DR   FLYBASE; FBgn0000039; nAcR-alpha-96Ab.
    DR   PROSITE; PS00236; NEUROTR_ION_CHANNEL; 1.
    DR   PFAM; PF00065; neur_chan; 1.
    KW   RECEPTOR; POSTSYNAPTIC MEMBRANE; IONIC CHANNEL; GLYCOPROTEIN; SIGNAL;
    KW   TRANSMEMBRANE; MULTIGENE FAMILY.
    FT   SIGNAL        1     41       PROBABLE.
    FT   CHAIN        42    576       ACETYLCHOLINE RECEPTOR PROTEIN, ALPHA-2.
    FT   DOMAIN       42    261       EXTRACELLULAR (POTENTIAL).
    FT   TRANSMEM    262    285       POTENTIAL.
    FT   TRANSMEM    293    311       POTENTIAL.
    FT   TRANSMEM    327    346       POTENTIAL.
    FT   DOMAIN      347    526       CYTOPLASMIC (POTENTIAL).
    FT   TRANSMEM    527    545       POTENTIAL.
    FT   DISULFID    169    183       BY SIMILARITY.
    FT   DISULFID    243    244       ASSOCIATED WITH RECEPTOR ACTIVATION
    FT                                (BY SIMILARITY).
    FT   CARBOHYD     65     65       POTENTIAL.
    FT   CARBOHYD    254    254       POTENTIAL.
    FT   CARBOHYD    570    570       POTENTIAL.
    SQ   SEQUENCE   576 AA;  65506 MW;  7B795689 CRC32;
         MAPGCCTTRP RPIALLAHIW RHCKPLCLLL VLLLLCETVQ ANPDAKRLYD DLLSNYNRLI
         RPVSNNTDTV LVKLGLRLSQ LIDLNLKDQI LTTNVWLEHE WQDHKFKWDP SEYGGVTELY
         VPSEHIWLPD IVLYNNADGE YVVTTMTKAI LHYTGKVVWT PPAIFKSSCE IDVRYFPFDQ
         QTCFMKFGSW TYDGDQIDLK HISQKNDKDN KVEIGIDLRE YYPSVEWDIL GVPAERHEKY
         YPCCAEPYPD IFFNITLRRK TLFYTVNLII PCVGISYLSV LVFYLPADSG EKIALCISIL
         LSQTMFFLLI SEIIPSTSLA LPLLGKYLLF TMLLVGLSVV ITIIILNIHY RKPSTHKMRP
         WIRSFFIKRL PKLLLMRVPK DLLRDLAANK INYGLKFSKT KFGQALMDEM QMNSGGSSPD
         SLRRMQGRVG AGGCNGMHVT TATNRFSGLV GALGGGLSTL SGYNGLPSVL SGLDDSLSDV
         AARKKYPFEL EKAIHNVMFI QHHMQRQDEF NAEDQDWGFV AMVMDRLFLW LFMIASLVGT
         FVILGEAPSL YDDTKAIDVQ LSDVAKQIYN LTEKKN
    //

## Output file format

The output is a standard EMBOSS report file.

The results can be output in one of several styles by using the command-line qualifier -rformat xxx, where 'xxx' is replaced by the name of the required format. The available format names are: embl, genbank, gff, pir, swiss, trace, listfile, dbmotif, diffseq, excel, feattable, motif, regions, seqtable, simple, srs, table, tagseq

See: http://emboss.sf.net/docs/themes/ReportFormats.html for further information on report formats.

By default sigcleave writes a 'motif' report file.

### Output files for usage example

### File: ach2_drome.sig

    ########################################
    # Program: sigcleave
    # Rundate: Fri Jul 15 2005 12:00:00
    # Report_format: motif
    # Report_file: ach2_drome.sig
    ########################################

    #=======================================
    #
    # Sequence: ACH2_DROME     from: 1   to: 576
    # HitCount: 9
    #
    # Reporting scores over 3.50
    #
    #=======================================

    (1) Score 13.739 length 13 at residues 29->41
     Sequence: LLVLLLLCETVQA
               |           |
              29           41
     mature_peptide: NPDAKRLYDDLLSNYNRLIRPVSNNTDTVLVKLGLRLSQLIDLNLKDQIL

    (2) Score 12.135 length 13 at residues 26->38
     Sequence: LCLLLVLLLLCET
               |           |
              26           38
     mature_peptide: VQANPDAKRLYDDLLSNYNRLIRPVSNNTDTVLVKLGLRLSQLIDLNLKD

    (3) Score 10.465 length 13 at residues 28->40
     Sequence: LLLVLLLLCETVQ
               |           |
              28           40
     mature_peptide: ANPDAKRLYDDLLSNYNRLIRPVSNNTDTVLVKLGLRLSQLIDLNLKDQI

    (4) Score 7.360 length 13 at residues 528->540
     Sequence: FLWLFMIASLVGT
               |           |
             528           540
     mature_peptide: FVILGEAPSLYDDTKAIDVQLSDVAKQIYNLTEKKN

    (5) Score 6.981 length 13 at residues 330->342
     Sequence: FTMLLVGLSVVIT
               |           |
             330           342
     mature_peptide: IIILNIHYRKPSTHKMRPWIRSFFIKRLPKLLLMRVPKDLLRDLAANKIN

    (6) Score 5.057 length 13 at residues 24->36
     Sequence: KPLCLLLVLLLLC
               |           |
              24           36
     mature_peptide: ETVQANPDAKRLYDDLLSNYNRLIRPVSNNTDTVLVKLGLRLSQLIDLNL

    (7) Score 4.026 length 13 at residues 31->43
     Sequence: VLLLLCETVQANP
               |           |
              31           43
     mature_peptide: DAKRLYDDLLSNYNRLIRPVSNNTDTVLVKLGLRLSQLIDLNLKDQILTT

    (8) Score 3.751 length 13 at residues 527->539
     Sequence: LFLWLFMIASLVG
               |           |
             527           539
     mature_peptide: TFVILGEAPSLYDDTKAIDVQLSDVAKQIYNLTEKKN

    (9) Score 3.632 length 13 at residues 308->320
     Sequence: LLISEIIPSTSLA
               |           |
             308           320
     mature_peptide: LPLLGKYLLFTMLLVGLSVVITIIILNIHYRKPSTHKMRPWIRSFFIKRL

    #---------------------------------------
    #---------------------------------------

## Data files

EMBOSS data files are distributed with the application and stored in the standard EMBOSS data directory, which is defined by the EMBOSS environment variable EMBOSS_DATA.

To see the available EMBOSS data files, run:

    % embossdata -showall

To fetch one of the data files (for example 'Exxx.dat') into your current directory for you to inspect or modify, run:

    % embossdata -fetch -file Exxx.dat

Users can provide their own data files in their own directories. Project specific files can be put in the current directory, or for tidier directory listings in a subdirectory called ".embossdata". Files for all EMBOSS runs can be put in the user's home directory, or again in a subdirectory called ".embossdata".

The directories are searched in the following order:

- . (your current directory)
- .embossdata (under your current directory)
- ~/ (your home directory)
- ~/.embossdata

Here is the default file for eukaryotic signals:

    # Amino acid counts for 161 Eukaryotic Signal Peptides,
    # from von Heijne (1986), Nucl. Acids. Res. 14:4683-4690
    #
    # The cleavage site is between +1 and -1
    #
    Sample: 161 aligned sequences
    #
    # R -13 -12 -11 -10  -9  -8  -7  -6  -5  -4  -3  -2  -1  +1  +2 Expect
    # - --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ------
      A  16  13  14  15  20  18  18  17  25  15  47   6  80  18   6  14.5
      C   3   6   9   7   9  14   6   8   5   6  19   3   9   8   3   4.5
      D   0   0   0   0   0   0   0   0   5   3   0   5   0  10  11   8.9
      E   0   0   0   1   0   0   0   0   3   7   0   7   0  13  14  10.0
      F  13   9  11  11   6   7  18  13   4   5   0  13   0   6   4   5.6
      G   4   4   3   6   3  13   3   2  19  34   5   7  39  10   7  12.1
      H   0   0   0   0   0   1   1   0   5   0   0   6   0   4   2   3.4
      I  15  15   8   6  11   5   4   8   5   1  10   5   0   8   7   7.4
      K   0   0   0   1   0   0   1   0   0   4   0   2   0  11   9  11.3
      L  71  68  72  79  78  45  64  49  10  23   8  20   1   8   4  12.1
      M   0   3   7   4   1   6   2   2   0   0   0   1   0   1   2   2.7
      N   0   1   0   1   1   0   0   0   3   3   0  10   0   4   7   7.1
      P   2   0   2   0   0   4   1   8  20  14   0   1   3   0  22   7.4
      Q   0   0   0   1   0   6   1   0  10   8   0  18   3  19  10   6.3
      R   2   0   0   0   0   1   0   0   7   4   0  15   0  12   9   7.6
      S   9   3   8   6  13  10  15  16  26  11  23  17  20  15  10  11.4
      T   2  10   5   4   5  13   7   7  12   6  17   8   6   3  10   9.7
      V  20  25  15  18  13  15  11  27   0  12  32   3   0   8  17  11.1
      W   4   3   3   1   1   2   6   3   1   3   0   9   0   2   0   1.8
      Y   0   1   4   0   0   1   3   1   1   2   0   5   0   1   7   5.6

## Notes

The value of minweight should be at least 3.5. At this level, the method should correctly identify 95% of signal peptides, and reject 95% of non-signal peptides. The cleavage site should be correctly predicted in 75-80% of cases.

If you use matrix tables with a different number of residues before or after the cleavage site, you must also set the advanced parameters nval and pval.

## References

1. von Heijne, G. "A new method for predicting signal sequence cleavage sites" Nucleic Acids Res.: 14:4683 (1986)
2. von Heijne, G. "Sequence Analysis in Molecular Biology: Treasure Trove or Trivial Pursuit" (Acad. Press, (1987), 113-117)

## Warnings

The program will warn you if a nucleic acid sequence is given or if the data file is not mathematically accurate.

## Diagnostic Error Messages

## Exit status

It exits with status 0 unless an error is reported.

## Known bugs

None.

## See also

Program name | Description
--- | ---
antigenic | Finds antigenic sites in proteins
digest | Protein proteolytic enzyme or reagent cleavage digest
epestfind | Finds PEST motifs as potential proteolytic cleavage sites
fuzzpro | Protein pattern search
fuzztran | Protein pattern search after translation
helixturnhelix | Report nucleic acid binding motifs
oddcomp | Find protein sequence regions with a biased composition
patmatdb | Search a protein sequence with a motif
patmatmotifs | Search a PROSITE motif database with a protein sequence
pepcoil | Predicts coiled coil regions
preg | Regular expression search of a protein sequence
pscan | Scans proteins using PRINTS

## Author(s)

Alan Bleasby (ajb © ebi.ac.uk)
European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK

Original program "SIGCLEAVE" (EGCG 1989) by Peter Rice (pmr © ebi.ac.uk)
Informatics Division, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK

## History

Completed 10th March 1999

## Target users

This program is intended to be used by everyone and everything, from naive users to embedded scripts.

## Comments

None