EMBOSS Cpgplot


Identify and plot CpG islands in nucleotide sequence(s)

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How to use this tool

Running a tool from the web form is a simple multiple steps process, starting at the top of the page and following the steps to the bottom.

Each tool has at least 2 steps, but most of them have more:

  • The first steps are usually where the user sets the tool input (e.g. sequences, databases...)
  • In the following steps, the user has the possibility to change the default tool parameters
  • And finally, the last step is always the tool submission step, where the user can specify a title to be associated with the results and an email address for email notification. Using the submit button will effectively submit the information specified previously in the form to launch the tool on the server

Note that the parameters are validated prior to launching the tool on the server and in the event of a missing or wrong combination of parameters, the user will be notified directly in the form.

Step 1 - Input Sequence

Sequence Input Form

One or more sequences to be analysed can be entered directly into this form. Sequences can be be in GCG, FASTA, EMBL, GenBank, PIR, NBRF, PHYLIP or UniProtKB/Swiss-Prot format. Partially formatted sequences are not accepted.

Sequence File Upload

A file containing a valid sequence in any protein sequence format (eg. FASTA or UniProtKB/Swiss-Prot) can be uploaded and used as input. Word processor files may yield unpredictable results as hidden/control characters may be present in the files. It is best to save files with the Unix format option to avoid hidden Windows characters.

Step 2 - Set Parameters

Window Size

The percentage CG content and the Observed frequency of CG is calculated within a window whose size is set by this parameter. The window is moved down the sequence and these statistics are calculated at each position that the window is moved to

Default value is: 100

Minimum length of an island

This sets the minimum length that a CpG island has to be before it is reported.

Default value is: 200

Minimum observed/expected

This sets the minimum average observed to expected ratio of C plus G to CpG in a set of 10 windows that are required before a CpG island is reported.

Default value is: 0.6

Minimum percentage

This sets the minimum average percentage of G plus C a set of 10 windows that are required before a CpG island is reported.

Default value is: 50.

Step 3 - Submission

Job title

It's possible to identify the tool result by giving it a name. This name will be associated to the results and might appear in some of the graphical representations of the results.

Email Notification

Running a tool is usually an interactive process, the results are delivered directly to the browser when they become available. Depending on the tool and its input parameters, this may take quite a long time. It's possible to be notified by email when the job is finished by simply ticking the box "Be notified by email". An email with a link to the results will be sent to the email address specified in the corresponding text box. Email notifications require valid email addresses.

Email Address

If email notification is requested, then a valid Internet email address in the form joe@example.org must be provided. This is not required when running the tool interactively (The results will be delivered to the browser window when they are ready).


EMBOSS: the European Molecular Biology Open Software Suite.
(2000 Jun) Trends in genetics : TIG 16 (6) :276-7
A new bioinformatics analysis tools framework at EMBL-EBI.
(2010 Jul) Nucleic acids research 38 (Web Server issue) :W695-9
Analysis Tool Web Services from the EMBL-EBI.
(2013 Jul) Nucleic acids research 41 (Web Server issue) :W597-600