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An analysis of single amino acid repeats as use case for application specific background models
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Łabaj, Paweł P, Sykacek, Peter and Kreil, David (2011) An analysis of single amino acid repeats as use case for application specific background models. BMC Bioinformatics, Vol.12 (No.1). p. 173. doi:10.1186/1471-2105-12-173 ISSN 1471-2105.
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Official URL: http://dx.doi.org/10.1186/1471-2105-12-173
Abstract
Background
Sequence analysis aims to identify biologically relevant signals against a backdrop of functionally meaningless variation. Increasingly, it is recognized that the quality of the background model directly affects the performance of analyses. State-of-the-art approaches rely on classical sequence models that are adapted to the studied dataset. Although performing well in the analysis of globular protein domains, these models break down in regions of stronger compositional bias or low complexity. While these regions are typically filtered, there is increasing anecdotal evidence of functional roles. This motivates an exploration of more complex sequence models and application-specific approaches for the investigation of biased regions.
Results
Traditional Markov-chains and application-specific regression models are compared using the example of predicting runs of single amino acids, a particularly simple class of biased regions. Cross-fold validation experiments reveal that the alternative regression models capture the multi-variate trends well, despite their low dimensionality and in contrast even to higher-order Markov-predictors. We show how the significance of unusual observations can be computed for such empirical models. The power of a dedicated model in the detection of biologically interesting signals is then demonstrated in an analysis identifying the unexpected enrichment of contiguous leucine-repeats in signal-peptides. Considering different reference sets, we show how the question examined actually defines what constitutes the 'background'. Results can thus be highly sensitive to the choice of appropriate model training sets. Conversely, the choice of reference data determines the questions that can be investigated in an analysis.
Conclusions
Using a specific case of studying biased regions as an example, we have demonstrated that the construction of application-specific background models is both necessary and feasible in a challenging sequence analysis situation.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- ) | ||||
Journal or Publication Title: | BMC Bioinformatics | ||||
Publisher: | BioMed Central Ltd. | ||||
ISSN: | 1471-2105 | ||||
Official Date: | 19 May 2011 | ||||
Dates: |
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Volume: | Vol.12 | ||||
Number: | No.1 | ||||
Page Range: | p. 173 | ||||
DOI: | 10.1186/1471-2105-12-173 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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