tcode.txt

emboss的linux版本的源代码

                                   tcode 



Function

   Fickett TESTCODE statistic to identify protein-coding DNA

Description

   tcode tests DNA sequences for protein coding regions using an
   algorithm which looks for simple and universal differences between
   protein-coding and noncoding DNA.The original paper reports that the
   test had been thoroughly proven on 400,000 bases of sequence data: it
   misclassifies 5% of the regions tested and gives an answer of "No
   Opinion" one fifth of the time.

   The program slides a window of user-selectable size over the DNA
   sequence. For each window the TESTCODE statistic is applied. The
   results can be output as a text report or displayed graphically. The
   text output reports each window as "Coding", "Noncoding" or "No
   opinion". Entries marked "No opinion" have a TESTCODE value that falls
   between the maximum and minimum values required to report a region as
   noncoding or coding. For the graphical plot, all points above a green
   horizontal line are determined to be coding regions. Those below a red
   line are determined to be noncoding. Points between the red and green
   lines are "no opinion" ones.

Biological Relevance

   The statistic reflects the fact that codons are used with unequal
   frequency and that oligonucleotides and nucleotides tend to be
   repeated with a periodicity of three.

   This application can assist in determining the probability of a region
   of nucleic sequence encoding a functional protein.

Algorithm

   The Fickett (1982) algorithm is used (1).

   A window of at least 200 bases is moved over the sequence in steps of
   3 bases

   Let:

  A1 = Number of A's in positions 1,4,7 ...
  A2 = Number of A's in positions 2,5,8 ...
  A3 = Number of A's in positions 3,6,9 ...

   A position value is determined that reflects the degree to which each
   base is favoured in one codon position over another, i.e.

  Apos = MAX(A1,A2,A3) / MIN(A1,A2,A3)+1

   This is done for all 4 bases. The percentage composition of each base
   is also determined. Eight values are therefore determined, four
   position values and four composition values. These are then converted
   to probabilities (p) of coding using a look-up table provided as the
   data file for the program. The values in this look-up table have been
   determined experimentally using known coding and noncoding sequences.

   Each of the probabilities is multiplied by a weight (w) value (again
   from the look-up table) for the respective base. The weight value
   reflects the percentage of the time that each parameter alone
   successfully predicted coding or noncoding function for the sequences
   of known function.

   The TESTCODE statistic is then:

  p1w1 + p2w2 + p3w3 + p4w4 + p5w5 + p6w6 + p7w7 + p8w8

   A result of less than 0.74 is probably a non-coding region.
   A result equal or greater than 0.95 is probably a coding region.
   Anything in between these two values is uncertain.

Usage

   Here is a sample session with tcode


% tcode 
Fickett TESTCODE statistic to identify protein-coding DNA
Input nucleotide sequence(s): tembl:hsfau1
Length of sliding window [200]: 
Output report [hsfau1.tcode]: 

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

   Example 2

   Produce a graphical plot


% tcode -plot -graph cps 
Fickett TESTCODE statistic to identify protein-coding DNA
Input nucleotide sequence(s): tembl:hsfau1
Length of sliding window [200]: 

Created tcode.ps

   Go to the output files for this example

Command line arguments

   Standard (Mandatory) qualifiers (* if not always prompted):
  [-sequence]          seqall     Nucleotide sequence(s) filename and optional
                                  format, or reference (input USA)
   -window             integer    [200] This is the number of nucleotide bases
                                  over which the TESTCODE statistic will be
                                  performed each time. The window will then
                                  slide along the sequence, covering the same
                                  number of bases each time. (Integer 200 or
                                  more)
*  -outfile            report     [*.tcode] Output report file name
*  -graph              xygraph    [$EMBOSS_GRAPHICS value, or x11] Graph type
                                  (ps, hpgl, hp7470, hp7580, meta, cps, x11,
                                  tekt, tek, none, data, xterm, png)

   Additional (Optional) qualifiers: (none)
   Advanced (Unprompted) qualifiers:
   -datafile           datafile   [Etcode.dat] The default data file is
                                  Etcode.dat and contains coding probabilities
                                  for each base. The probabilities are for
                                  both positional and compositional
                                  information.
   -step               integer    [3] The selected window will, by default,
                                  slide along the nucleotide sequence by three
                                  bases at a time, retaining the frame
                                  (although the algorithm is not frame
                                  sensitive). This may be altered to increase
                                  or decrease the increment of the slide.
                                  (Integer 1 or more)
   -plot               toggle     [N] On selection a graph of the sequence (X
                                  axis) plotted against the coding score (Y
                                  axis) will be displayed. Sequence above the
                                  green line is coding, that below the red
                                  line is non-coding.

   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
   -rformat            string     Report format
   -rname              string     Base file name
   -rextension         string     File name extension
   -rdirectory         string     Output directory
   -raccshow           boolean    Show accession number in the report
   -rdesshow           boolean    Show description in the report
   -rscoreshow         boolean    Show the score in the report
   -rusashow           boolean    Show the full USA in the report
   -rmaxall            integer    Maximum total hits to report
   -rmaxseq            integer    Maximum hits to report for one sequence

   "-graph" associated qualifiers
   -gprompt            boolean    Graph prompting
   -gdesc              string     Graph description
   -gtitle             string     Graph title
   -gsubtitle          string     Graph subtitle
   -gxtitle            string     Graph x axis title
   -gytitle            string     Graph y axis title
   -goutfile           string     Output file for non interactive displays
   -gdirectory         string     Output directory

   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 dying program messages

Input file format

   tcode reads any normal sequence USAs.

   The program will ignore ambiguity codes in the nucleic acid sequence
   and just accept the four common bases. This is a function of the
   algorithm, and the data tables.

  Input files for usage example

   'tembl:hsfau1' is a sequence entry in the example nucleic acid
   database 'tembl'

  Database entry: tembl:hsfau1

ID   HSFAU1     standard; DNA; HUM; 2016 BP.
XX
AC   X65921; S45242;
XX
SV   X65921.1
XX
DT   13-MAY-1992 (Rel. 31, Created)
DT   21-JUL-1993 (Rel. 36, Last updated, Version 5)
XX
DE   H.sapiens fau 1 gene
XX
KW   fau 1 gene.
XX
OS   Homo sapiens (human)
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia
;
OC   Eutheria; Primates; Catarrhini; Hominidae; Homo.
XX
RN   [1]
RP   1-2016
RA   Kas K.;
RT   ;
RL   Submitted (29-APR-1992) to the EMBL/GenBank/DDBJ databases.
RL   K. Kas, University of Antwerp, Dept of Biochemistry T3.22,
RL   Universiteitsplein 1, 2610 Wilrijk, BELGIUM
XX
RN   [2]
RP   1-2016
RX   MEDLINE; 92412144.
RA   Kas K., Michiels L., Merregaert J.;
RT   "Genomic structure and expression of the human fau gene: encoding the
RT   ribosomal protein S30 fused to a ubiquitin-like protein.";
RL   Biochem. Biophys. Res. Commun. 187:927-933(1992).
XX
DR   SWISS-PROT; P35544; UBIM_HUMAN.
DR   SWISS-PROT; Q05472; RS30_HUMAN.
XX
FH   Key             Location/Qualifiers
FH
FT   source          1..2016
FT                   /db_xref="taxon:9606"
FT                   /organism="Homo sapiens"
FT                   /clone_lib="CML cosmid"
FT                   /clone="15.1"
FT   mRNA            join(408..504,774..856,951..1095,1557..1612,1787..>1912)
FT                   /gene="fau 1"
FT   exon            408..504
FT                   /number=1
FT   intron          505..773
FT                   /number=1
FT   exon            774..856


  [Part of this file has been deleted for brevity]

FT                   RAKRRMQYNRRFVNVVPTFGKKKGPNANS"
FT   intron          857..950
FT                   /number=2
FT   exon            951..1095
FT                   /number=3
FT   intron          1096..1556
FT                   /number=3
FT   exon            1557..1612
FT                   /number=4
FT   intron          1613..1786
FT                   /number=4
FT   exon            1787..>1912
FT                   /number=5
FT   polyA_signal    1938..1943
XX
SQ   Sequence 2016 BP; 421 A; 562 C; 538 G; 495 T; 0 other;
     ctaccatttt ccctctcgat tctatatgta cactcgggac aagttctcct gatcgaaaac        6
0
     ggcaaaacta aggccccaag taggaatgcc ttagttttcg gggttaacaa tgattaacac       12
0
     tgagcctcac acccacgcga tgccctcagc tcctcgctca gcgctctcac caacagccgt       18
0
     agcccgcagc cccgctggac accggttctc catccccgca gcgtagcccg gaacatggta       24
0
     gctgccatct ttacctgcta cgccagcctt ctgtgcgcgc aactgtctgg tcccgccccg       30
0
     tcctgcgcga gctgctgccc aggcaggttc gccggtgcga gcgtaaaggg gcggagctag       36
0
     gactgccttg ggcggtacaa atagcaggga accgcgcggt cgctcagcag tgacgtgaca       42
0
     cgcagcccac ggtctgtact gacgcgccct cgcttcttcc tctttctcga ctccatcttc       48
0
     gcggtagctg ggaccgccgt tcaggtaaga atggggcctt ggctggatcc gaagggcttg       54
0
     tagcaggttg gctgcggggt cagaaggcgc ggggggaacc gaagaacggg gcctgctccg       60
0
     tggccctgct ccagtcccta tccgaactcc ttgggaggca ctggccttcc gcacgtgagc       66
0
     cgccgcgacc accatcccgt cgcgatcgtt tctggaccgc tttccactcc caaatctcct       72
0
     ttatcccaga gcatttcttg gcttctctta caagccgtct tttctttact cagtcgccaa       78
0
     tatgcagctc tttgtccgcg cccaggagct acacaccttc gaggtgaccg gccaggaaac       84
0
     ggtcgcccag atcaaggtaa ggctgcttgg tgcgccctgg gttccatttt cttgtgctct       90
0
     tcactctcgc ggcccgaggg aacgcttacg agccttatct ttccctgtag gctcatgtag       96
0
     cctcactgga gggcattgcc ccggaagatc aagtcgtgct cctggcaggc gcgcccctgg      102
0
     aggatgaggc cactctgggc cagtgcgggg tggaggccct gactaccctg gaagtagcag      108
0
     gccgcatgct tggaggtgag tgagagagga atgttctttg aagtaccggt aagcgtctag      114
0
     tgagtgtggg gtgcatagtc ctgacagctg agtgtcacac ctatggtaat agagtacttc      120
0
     tcactgtctt cagttcagag tgattcttcc tgtttacatc cctcatgttg aacacagacg      126
0
     tccatgggag actgagccag agtgtagttg tatttcagtc acatcacgag atcctagtct      132
0
     ggttatcagc ttccacacta aaaattaggt cagaccaggc cccaaagtgc tctataaatt      138
0
     agaagctgga agatcctgaa atgaaactta agatttcaag gtcaaatatc tgcaactttg      144
0
     ttctcattac ctattgggcg cagcttctct ttaaaggctt gaattgagaa aagaggggtt      150
0