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Scan for Motifs help :

Scan for Motifs is an approach to simplify the process of identifying a wide range of regulatory elements in RNA. It can also be used to search any nucleotide sequences. It is particularly useful for RNA-binding protein sites (RBPDB), Translational control elements (Transterm), targets of conserved miRNA families (TargetScan) as well as 6-8 base long miRNA seed sequence targets (mirBase) on alignments of 3' UTR sequences

The standalone webserver is here and is also part of the Transterm site.

Please cite: Biswas, A. and C. M. Brown (2014) Scan for Motifs: a webserver for the analysis of post-transcriptional regulatory elements in the 3' untranslated regions (3' UTRs) of mRNAs BMC Bioinformatics 15: 174.link

For enquiries please contact Ambarish Biswas or Dr. Chris Brown

Last update 26/4/2018

   Input section:
The input section of Scan for motifs is shown in the image below.

  1. Enter a human gene symbol (e.g. "TNF") :  

This option allows users to type in a human gene symbol (e.g. TNF, LIN28A etc). The input is not case sensitive. This is a real time search to the associated table, and while typing the program will show 10 matches beginning with the typed letters. If user wants to see a list of genes containing a search term, he/she can achieve that, by adding a "%" sign before the search term. For example, typing "%28a" will populate a list like the one shown in the image below.
The user can click on any item from the dropdown list, and the corresponding UTR sequences will be retrieved and added to the analysis as input sequence. Multiple selection is not possible in this form, and if the user wants to try another search, the previously typed letters should be cleared. If there are multiple UTRs from the same gene (e.g. SLC28A3-NM_001199633 and NM_022127), searching for just the gene name e.g. SLC28A3, will return both UTRs in the alignment. In this case however both UTRs were identical, so they align. If two UTRs are dissimilar they will not align, but the presence and absence of predicted elements in both will be shown.

  1. Paste or upload a file in one of the supported formats.

The following formats are accepted:

   FASTA/MultiFASTA format:
 
About FASTA format FASTA format is a text-based format for representing either nucleotide sequences or peptide sequences, in which nucleotides or amino acids are represented using single-letter codes. The format also allows for sequence names and comments to precede the sequences. The format originates from the FASTA software package, but has now become a standard in the field of bioinformatics. more info.
 
Example:

>SEQUENCE_1
UGGCCACCACCUGGAAUUCAGAAUGGGGCGCCCAGAACGCACCAGGGCCUGGGGUUGGGAUUCCCGAGUGGGAGCCCUUGGGGCGCUGGGAAUGCGGAGGCCGGGGCUGCUUUGGCUCCUGUCAGAGCCCUUCGGCCAUCCCUGACCU
AGAACCUGACGUGAGUGGACCCCAGACCUCCCGCUCUCCAGGUGUUUCCAGACUGUUCCCUGAGAGCGGAGCCCAGCCCCUGCCCCUCCCCACAGGACGCACUCCCUAUUUAUGUUUGCACUAGAGGUUAUUUAUUAUUUAUUUAUUA
UUUAUUUAUUGACCAAUUAACUUAUUUAUUCGGGAGGUUGGGGUGUCCCAGGGGACCCAGCGUAGGGACAGCCUUGGCUCUGGCGUGUUUUCUGUGAAAACGGAGCCGAGCCGUGGGCUGCUCCCCCUUGGCCUCCUGGCCUCCGUGC
CUCCCUUCGCUUAUGUUUUGAAGAAAUAUUUAUCUGAUCAAGUUGUCUGAAUAAUGCUGAUUUGGUGACAGGCUGUCGCUACAUCGCUGAACCUCUGCUCCCCAGGGGAGUUUUGUCUGUAACCGCCCUACUGGUCAGUGGCGAGAAA
UAAAAUGUGCUUAGAAAAG
>SEQUENCE_2
GGAGACUGGACAUUCAUCUUCACCUGGCUCAAAUCUUUUAGUAGCCACUCCUCCACACCCCCCUCCCCUAUUUAUUUCUGGUUUAGAAAGGGAAUUAGGGCCUCCGGGCCAGGCCCCAAGCUUGGAACUUUAAACAACAACACUUAAA
ACCUAGGAUGUGAAGAUGUAUGGCCUGAACAAUGGGGCACUGGCUACCACAUAGAGUUCAGACUAGGGCUCCCAGAACUCACUGGGAGUCUGAAAUCUGGAUUCCUGAGUGCAGCCUAGGACACCUGGAAUGUGCAAGUCAGGGAAUC
CUUGGUUCUGGUCAGAACAUCUCUUGAGAAGAUCUCACUUAGAACUUGACACAAGUGGACCUCAGGUCUCCCUUUCUUCAGAUGUCUCCAGACUCUCCUGAGAUGGAGAGCCCAGCCCCUCUUGUCUCCCACAGGGCCAGUUCUUUCU
AUUUAUGUUUGCACUUGUGAUUAUUUAUUAUUUAUUUAUUAUUUAUUUAUUUACUGAUAAACCUAUUUAUUCAGGAGGUUAGUGUGUCCUGGGAGAGCCAGCAGAGGGGCUGCCUUGGCUUAGACAUGUUUUCUAUGAAAACGGAGCU
GAACUAUAGGCUGUUCCCACCGGCCUCCAGGCCUCUGUGCCUUCUUUUGCAUAAUUUUGUUUUAAUUUAUCUGAUCAAGUUGUCUAAAUAAUGCUGAUUUGGUGACCUACUGUCGCUAUGUCGCUGAACCUCUGCUCCCCAGGGGAGU
UGUCUUUGUAAUCGCCCAACUGAUCAGUGGCGAAAAAUAAAGUGUGCUUGGAAGUG
>SEQUENCE_3
GGGGGAUGCAUGCAGAUCAUUCACCACCCAGCCCAUCGCCCUCCCUGUCCUGCCAUUCCCAUUGGGCCUCCUCGUCCCCGAAAGGAAGGGGGACGAGCCGGGUCUCUAAGUCAUCACCCCGAACAACAACACUUAGAACUUGAGAUGC
AAGGAUGUGUGACUCAGACCAGACCGGGGGCACUGACCACCGCAGCCUGGAAUCCAAACUGGGGCUUGCAGAACCCACUGGGUCUCCAGAUGCAAAUGGGGACACCUGAAAUGUGGAGGUCUCCUUGAGCCUCCGGCUCACUUCCGAA
GAUCUGAGGAGUCCUCACCCAGAACUUGGCAUGACCUCCGACCUCCCUUGCACCGAAAGUUUCUAGACCCUCCCCUAAGAGAUGAAGCCCCCCGCCACGUGGCACUAGUCAGCCCUCUAUUUAUGUUUGCACUGAGAAUUAUUUAUUA
UUUAUUAUUUAUAUAUUUAUUUAUUUCCUGGUGAAUGUAUUUAUUCAGGAGGUCGGGGAACCUGGGGGAUCCAGUGUUGGGGGUUGCCUGAGCUCAGACAUGUUUUCUAUGAAAAUGGAGCUGGAAUGUAGGCUGCUCCCACCCCGCU
UCCUGGCCUCCUUACCUCCCUGUGCUUGUGGAUUUAUCGAUCGAGUUGUCUGGAUAAUGCUGAUUUGGCGACAGACUGUUGCUAUCUCGCUGAACCUCUGCUCCCCAGGGGAGUUGUGCCUGUAAUCGUCCUACUGGUCAGUGGCGAA
AAAUAAAGUUUGCUUAGAAAAG

Sample MultiFASTA file

   Tabular MSA format:
 
This is very similar to ClustalW format, except that in this file there will be only one block of alignment. Each line of the alignment will have two columns. The first column contains the sequence identifier, and the second column contains aligned sequence. The sequence identifiers has to be unique.
 
Example:
Sample tabular MSA file

   ClustalW format:
 
Clustal is a widely used multiple sequence alignment computer program. The command line interface is called clustalW, and the output file (.aln) will begin with a header line contains "CLUSTAL". More details.
 
Example:
		
CLUSTAL 2.1 multiple sequence alignment


SEQUENCE_1      ------------------------------------------------------------
SEQUENCE_2      GGAGACUGGACAUUCAUCUUCACCUGGCUCAAAUCUUUUAGUAGCCACUCCUCCACACCC
SEQUENCE_3      ------GGGGGAUGCAUGCAGAUCAUUCACCACCCAGCCCAUCGCCCUCCCUGUCCUGCC
                                                                            

SEQUENCE_1      ------------------------------------------------------------
SEQUENCE_2      CCCUCCCCUAUUUAUUUCUGGUUUAGAAAGGGAAUUAGGGCCUCCGGGCCAGGCCCCAAG
SEQUENCE_3      AUUCCCAUUGGGCCUCCUCGUCCCCGAAAGGAAGGGGGA-----CGAGCCGGGUCUCUAA
                                                                            

SEQUENCE_1      ------------------------------------------------------------
SEQUENCE_2      CUUGGAACUUUAAACAACAACACUUAAAACCUAGGAUGUGAAGAUGUAUGGCCUGAACAA
SEQUENCE_3      GUCAUCACCCCGAACAACAACACUUAGAACUUGAGAUGCAAGGAUGUGUGACUCAGACCA
                                                                            

SEQUENCE_1      ------------UGGCCACCACC---UGGAAUUCAGAAUGGGGCGCCCAGAACGCACCAG
SEQUENCE_2      U----GGGGCACUGGCUACCACA---UAGAGUUCAGACUAGGGCUCCCAGAACUCACUGG
SEQUENCE_3      GACCGGGGGCACUGACCACCGCAGCCUGGAAUCCAAACUGGGGCUUGCAGAACCCACUGG
                            ** * *** *    * ** * ** * * ****   ****** ***  *

SEQUENCE_1      G-GCCUGGGGUUGGGAUUCCCGAGUGGGAGCCCUUGGGGCGCUGGGAAUGCGGAGGCCGG
SEQUENCE_2      GAGUCUGAAAUCUGGAUUCCUGAGUGCAG---CCUAGGACACCUGGAAUGUGCAAGUCAG
SEQUENCE_3      G---------------UCUCCAGAUGCAA---AUGGGGACACCUGAAAUGUGGAGGUCUC
                *               *  *    **          ** * *  * **** * * * *  

SEQUENCE_1      G--GCUGCUUUGGCUCCUGUCAGAGC--CCUUCGGCCAUCCCUGACCUAGAACCUGACGU
SEQUENCE_2      G--GAAUCCUUGGUUCUGGUCAGAACAUCUCUUGAGAAGAUCUCACUUAGAACUUGACAC
SEQUENCE_3      CUUGAGCCUCCGGCUCACUUCCGAAGA---UCUGAGGAGUCCUCACCCAGAACUUGGCAU
                   *   *   ** **   ** **         *   *   ** **  ***** ** *  

SEQUENCE_1      GAGUGGACCCCAGACCUCCCGCUCUCCAGGUGUUUCCAGACUGUUCCCUGAGA-GCGGAG
SEQUENCE_2      AAGUGGACCUCAGGUCUCCCUUUCUUCAGAUGUCUCCAGACUCU--CCUGAGAUGGAGAG
SEQUENCE_3      -----GACCUCCGACCUCCCUUGCACCGAAAGUUUCUAGACCCUCCCCUAAGAGAUGAAG
                     **** * *  *****   *  *    ** ** ****  *  *** ***     **

SEQUENCE_1      CCCAGCCCCUGCCCCUCCCCACAGGAC--GCACUCCCUAUUUAUGUUUGCACUAGAGGUU
SEQUENCE_2      CCCAGCCCCUCUUGUCUCCCACAGGGCCAGUUCUUUCUAUUUAUGUUUGCACUUGUGAUU
SEQUENCE_3      CCC----CCCGCCACGUGGCACUAGUC---AGCCCUCUAUUUAUGUUUGCACUGAGAAUU
                ***    **          ***  * *     *   *****************     **

SEQUENCE_1      AUUUAUUAUUUAUU---UAU-UAUUUAUUUAUUGACCAAUUAACUUAUUUAUUCGGGAGG
SEQUENCE_2      AUUUAUUAUUUAUU---UAU-UAUUUAUUUAUUUACUGAUAAACCUAUUUAUUCAGGAGG
SEQUENCE_3      AUUUAUUAUUUAUUAUUUAUAUAUUUAUUUAUUUCCUGGUGAAUGUAUUUAUUCAGGAGG
                **************   *** ************  *   * **  ********* *****

SEQUENCE_1      UUGGGGUGUCCCAGGGGACCCAGCGU-AGGGACAGCCUUGGCUCUGGCGUGUUUUCUGUG
SEQUENCE_2      UUAGUGUGUCCUGGGAGAGCCAGCAG-AGGGGCUGCCUUGGCUUAGACAUGUUUUCUAUG
SEQUENCE_3      UCGGGG-AACCUGGGGGAUCCAGUGUUGGGGGUUGCCUGAGCUCAGACAUGUUUUCUAUG
                *  * *   **  ** ** ****     ***   ****  ***  * * ******** **

SEQUENCE_1      AAAACGGAGCCGAGCCGUGGGCUGCUCCCCCUUGGCCUCCUGGCCUCCGUGCCUCCCUUC
SEQUENCE_2      AAAACGGAGCUGAACUAUAGGCUGUUCCCACC-GGCCUCCAGGCCUCUGUGCCUUCUUUU
SEQUENCE_3      AAAAUGGAGCUGGAAUGUAGGCUGCUCCCACCCCGCUUCCUGGCCUCCUUACCUCCCUGU
                **** ***** *     * ***** **** *   ** *** ******  * *** * *  

SEQUENCE_1      GCUUAUGUUUUGAAGAAAUAUUUAUCUGAUCAAGUUGUCUGAAUAAUGCUGAUUUGGUGA
SEQUENCE_2      GCAUA-AUUUUGUUUUAA--UUUAUCUGAUCAAGUUGUCUAAAUAAUGCUGAUUUGGUGA
SEQUENCE_3      GCUUG---------UGGA--UUUAUC-GAUCGAGUUGUCUGGAUAAUGCUGAUUUGGCGA
                ** *             *  ****** **** ********  *************** **

SEQUENCE_1      CAGGCUGUCGCUACAUCGCUGAACCUCUGCUCCCCAGGGGAGUUUUGUCUGUAACCGCCC
SEQUENCE_2      CCUACUGUCGCUAUGUCGCUGAACCUCUGCUCCCCAGGGGAGUUGUCUUUGUAAUCGCCC
SEQUENCE_3      CAGACUGUUGCUAUCUCGCUGAACCUCUGCUCCCCAGGGGAGUUGUGCCUGUAAUCGUCC
                *   **** ****  ***************************** *   ***** ** **

SEQUENCE_1      UACUGGUCAGUGGCGAGAAAUAAAAUGUGCUUAGAAAAG
SEQUENCE_2      AACUGAUCAGUGGCGAAAAAUAAAGUGUGCUUGGAAGUG
SEQUENCE_3      UACUGGUCAGUGGCGAAAAAUAAAGUUUGCUUAGAAAAG
                 **** ********** ******* * ***** ***  *
        
Sample ClustalW file

 
2.A Select all regulatory elements with a matching score <= per thousand bases from Transterm..

For all the elements provided by the Transterm database, their corresponding sequence pattern has been searched with Patsearch against dinucleotide shuffled sequences. The input sequence was 18,895 human UTRs from UCSC, made non-redundant. The average length was 1,281. The expected dinucleotide frequencies would be 0.0625 based on an equal amount of each base, however the dinucleotide frequencies were:
AA	0.088
AC	0.048
AG	0.068
AT	0.070
CA	0.068
CC	0.060
CG	0.012
CT	0.073
GA	0.057
GC	0.047
GG	0.057
GT	0.054
TA	0.061
TC	0.058
TG	0.078
TT	0.103
TT and AA were the most overrepresented (0.103,0.088), CG most underpresented (0.012). The average number of matches per 1000 bases was recorded as the expected number of hit that would occur by chance (E-value) in shuffled sequences. A E-value per thousand is used as this is the typical length of a human UTR when SFM is run in the default mode, requiring a match to the human reference sequence to show a match in the output. As some of these elements have quite short sequences of identity (e.g. 8 nt), there is a high probability of false positive identification. An 8 base exact match would be expected in a UTR with equal amounts of the four nucleotides to occur once in every 4096 bases, therefore about 0.25 times in a 1000 bases 3' UTR. The actual E-values in dinucleotide shuffled sequences are higher or lower as some dinucleotides (e.g. AA, TT) are more frequent. The E-value filter can be changed by modifying the value ( default: 0.175) in the corresponding text box with red border. By changing the E-value in the textbox (a smaller value increases stringency), all the elements will be checked to see if their E- value per thousand bases falls above the specified value. Only the elements that have E-values below or equal to the specified value will be automatically selected.

In section 2.A, every listed element has a small information icon at the end. By clicking on the icon, the user can refer to the complete details of the element without leaving the page (as shown in the right side image).

This could be used to input data from other experiments, e.g. those in RBPDB, or from other experimental studies, or simply to visualise a sequence of interest.

The user can also provide a custom sequence motif/pattern (e.g. 'GACTTT', or 'GAC 1....6 TT', or 'r1={au,ua,gc,cg,gu,ug,ga,ag} p1=2...3 0...4 p2=2...5 1...5 r1~p2 0...4 ~p1' or ^GTTGTT[1,0,0] ) to be included in the analysis. For a complete set of syntax rules refer to the original PatSearch paper (Grillo et al 2003) The user motif/pattern will be used along with the Transterm motifs (if any are selected) using PatSearch. In this case no E-value filer is applied. When the user is determining the biological significance of the result they should take into account the likelihood of a background match This is approximately 1/4096 for 6 nt of exact match (e.g. GACGTT, or GANNNCGNNTT), 1/16384 for 7 nt, and 1/65536 for 8 nt.

Cite: Jacobs, G.H., Chen, A., Stevens, S.G., Stockwell, P.A., Black, M.A., Tate, W.P. and Brown, C.M. (2009) Transterm: a database to aid the analysis of regulatory sequences in mRNAs, Nucleic acids research, 37, D72-76.

 
2.B Show protein binding sites from RBPDB for which frequency matrices are available with an E-value <=  

All 73 motifs from the RNA Binding Protein DB with PFM are included in SFM. The PFMs are searched against user input sequence using the command line version of MotifLocator (v3.2.0). Some of these PFM are short ~6-11 bases. The PFMs were searched against 10 randomly generated thousand base sequences and the occurrence per thousand bases was recorded. These E-values ranged from 0 to 44.

By modifying the E-value in the corresponding text box (a smaller value increases stringency) the user can omit matrices with high E-values. The default E-value cut off of 1 enables a search with approximately half the matrices.

It is also possible to use other binding sites from RBPDB by inputting the binding site sequences (e.g from the list of human RNA binding proteins here). An example would be the reported binding sites for YBX1. There are twelve reported sequences from different studies using different techniques (e.g. UCCAGCAA link).

Version: v1.3 release 28.09.2012

Cite: Cook, K.B., Kazan, H., Zuberi, K., Morris, Q. and Hughes, T.R. (2011) RBPDB: a database of RNA-binding specificities, Nucleic acids research, 39, D301-308.

 
2.C  Show targets of conserved microRNA families as predicted by Targetscan 

Targetscan is one of the most used and cited public database for microRNA binding site prediction and visualization, mainly focusing on orthologous 3’ UTRs of vertebrate sequences. It contains over 400 highly conserved targets of microRNA binding sites. All the "broadly conserved" and "conserved" microRNAs predicted target information (binding sites) and other associated files were obtained from the Targetscan website, processed and converted in the relational database table and added to Scan for Motifs.

Version: Release 6.2 (June 2012)

Cite: Garcia, D.M., Baek, D., Shin, C., Bell, G.W., Grimson, A. and Bartel, D.P. (2011) Weak seed-pairing stability and high target-site abundance decrease the proficiency of lsy-6 and other microRNAs, Nature structural & molecular biology, 18, 1139-1146.

 
2.D  Show all base seed sequence targets from human microRNA's (miRBase

To visualize all the potential targets of miRNA binding sites in user input sequence, we downloaded the mature miRNA sequence file (mature.fa) from miRBase website, processed the file (reverse complemented and extracted 8 5' bases) to get a list of 2042 eight base long seed sequences, stored in a reference table and added to Scan for motifs server. These motifs are searched in the user sequence using perl's regular expressions.

The user can choose to show either 6 or 7 or 8 base long binding site targets by changing the corresponding value from the drop down list, controlling the number of motifs to be identified and shown in the output. It is expected that there would be approximately 1/4096 for 6mer of exact match, 1/16384 for each of the two 7mers, and 1/65536 for 8mer. As there are ~2000 seeds to be searched with, matches to short (e.g. 6mer) seeds must be interpreted with caution. There would be about 30 matches in total per 1000 base UTR from 7mer seeds (Bonferroni correction for multiple testing). In order to avoid false positives only Watson-Crick, A-U and G-C, not G-U base pairing is allowed.

To distinguish the two 7mers, the notation A1 is used for the 7mer.A1 (base 1-7). On visualising these results the adjacent features searched bor by miRNA target prediction programs could be used. For example, TargetScan would use: conservation across species, position in the UTR and local composition (Garcia et al 2011).

Version: Release 20 (June 2013)

Cite: Kozomara, A. and Griffiths-Jones, S. (2011) miRBase: integrating microRNA annotation and deep-sequencing data, Nucleic acids research, 39, D152-157.

 
E.  Include elements that is not found in the reference sequence. 

This option is applicable when a MultiFASTA/tabular MSA/ClustalW alignment is given as input. If a human gene symbol was used to get the sequence, the human UTR sequence will be the reference sequence. For any other cases, the top sequence will be used as the reference sequence. By default this allows the user to filter out the elements not found in the reference sequence. However, if user does not want to use a reference sequence, he/she should leave the option unselected and the program will show all the elements identified in all the sequence. Note that this will increase the number of hits, and false positives.

Output screen
Example output and description 

The image on the right shows a typical "Scan for motif" output. Each type of regulatory element is grouped based on their source, and the identified elements are listed as links in the corresponding sections. The small icons on the right of these elements are linked to their sources.

The square color boxes represent the colored codes of the corresponding elements. This means, every Transterm element has been highlighted with yellow color in the sequence. This highlight is partially transparent, allowing the user the ability to see all the other overlapping elements. The height of this colored boxes have different height, and presented in such layered way, that the user can mouse over on each element.

Each identified element is linked to the first occurrene of that element in the sequence. Clicking on the element takes the current view point to the section.

Because the miRBase seed sequences are only 6-8 bases long, they are the most frequently occuring elements in any general analysis (except FDR rate set to 3 or 3.5), The identified miRBase element section often contains so many identified elements, that user needs to scroll to see elements on the top list and their corresponding position in the sequence. To avoid this, the user may click on the plus/minus icon next to the "Blue square" on the right of "Identified 8 base seed sequence targets from human microRNA's (miRBase) :". This will toggle the view of miRBase elements.

The bottom section shows the input sequence(s), highlighting every identified element. Placing the mouse on these colored boxes shows the element name and the motif sequence.By clicking on these colored boxes the user can see how many times and where in the input sequence this element was found.

Finally, a detailed analysis report can be downloaded by clicking on the blue button named "Download complete Report and Sequences", which can very useful, particularly for two reasons. One, it has all the input parameters and sequences, which will allow the user to get all the experiment details in the future. Two, the identified elements are presented in "BED" format, allowing user to export the relative section(s) into other formats.

A sample report can be obtained from this Link.

  References : 

Places to start, reviews

Stevens, S. and C. Brown (2014). Bioinformatic methods to discover cis-regulatory elements in mRNAs. Springer Handbook of Bio-/Neuro-informatics. N. Kasabov. Heidelberg, Springer: 151-169.

Quattrone, A. and E. Dassi (2016) Introduction to Bioinformatics Resources for Post-transcriptional Regulation of Gene Expression (2016) Methods Mol Biol 1358: 3-28.

Specific Resources

Giudice, G., F. Sanchez-Cabo, C. Torroja and E. Lara-Pezz ATtRACT-a database of RNA-binding proteins and associated motifs (2016) Database (Oxford) April 2016.

Chang, T.H., Huang, H.Y., Hsu, J.B., Weng, S.L., Horng, J.T. and Huang, H.D. (2013) An enhanced computational platform for investigating the roles of regulatory RNA and for identifying functional RNA motifs, BMC bioinformatics, 14 Suppl 2, S4.

Claeys, M., Storms, V., Sun, H., Michoel, T. and Marchal, K. (2012) MotifSuite: workflow for probabilistic motif detection and assessment, Bioinformatics, 28, 1931-1932.

Cook, K.B., Kazan, H., Zuberi, K., Morris, Q. and Hughes, T.R. (2011) RBPDB: a database of RNA-binding specificities, Nucleic acids research, 39, D301-308.

Dassi, E., Malossini, A., Re, A., Mazza, T., Tebaldi, T., Caputi, L. and Quattrone, A. (2012) AURA: Atlas of UTR Regulatory Activity, Bioinformatics, 28, 142-144.

Garcia, D.M., Baek, D., Shin, C., Bell, G.W., Grimson, A. and Bartel, D.P. (2011) Weak seed-pairing stability and high target-site abundance decrease the proficiency of lsy-6 and other microRNAs, Nature structural & molecular biology, 18, 1139-1146.

Griffiths-Jones, S., Grocock, R.J., van Dongen, S., Bateman, A. and Enright, A.J. (2006) miRBase: microRNA sequences, targets and gene nomenclature, Nucleic acids research, 34, D140-144.

Grillo, G., Licciulli, F., Liuni, S., Sbisa, E. and Pesole, G. (2003) PatSearch: A program for the detection of patterns and structural motifs in nucleotide sequences, Nucleic acids research, 31, 3608-3612.

Grillo, G., et al. (2010) UTRdb and UTRsite (RELEASE 2010): a collection of sequences and regulatory motifs of the untranslated regions of eukaryotic mRNAs, Nucleic acids research, 38, D75-80.

Gruber, A.R., Fallmann, J., Kratochvill, F., Kovarik, P. and Hofacker, I.L. (2011) AREsite: a database for the comprehensive investigation of AU-rich elements, Nucleic acids research, 39, D66-69.

Jacobs, G.H., Chen, A., Stevens, S.G., Stockwell, P.A., Black, M.A., Tate, W.P. and Brown, C.M. (2009) Transterm: a database to aid the analysis of regulatory sequences in mRNAs, Nucleic acids research, 37, D72-76.

Kozomara, A. and Griffiths-Jones, S. (2011) miRBase: integrating microRNA annotation and deep-sequencing data, Nucleic acids research, 39, D152-157.

Lewis, B.P., Burge, C.B. and Bartel, D.P. (2005) Conserved seed pairing, often flanked by adenosines, indicates that thousands of human genes are microRNA targets, Cell, 120, 15-20.