pfilt

pfilt masks regions of protein sequences that confound homology searches by replacing low-complexity segments, coiled-coil domains, and compositionally biased stretches with 'X' to improve downstream analyses.

Key Features:

• Low-complexity masking: Identifies and replaces low complexity regions in protein sequences with 'X' characters to reduce noise in sequence comparisons.
• Coiled-coil region masking: Detects and masks coiled-coil domains to prevent spurious matches driven by repetitive structural motifs.
• Compositional bias handling: Selectively masks overrepresented amino acids in regions with extreme amino acid composition to mitigate compositional bias effects on alignments.

Scientific Applications:

• Homology searches: Improves the accuracy of homology searches such as PSI-Blast by reducing false positives from low-complexity, coiled-coil, and compositionally biased regions.
• Sequence analysis and annotation: Preprocesses protein sequences to reduce artifacts from sequence complexity and bias prior to detailed annotation and comparative analyses.

Methodology:

Identifies low complexity regions, coiled-coil domains, and compositionally biased segments using predefined criteria and replaces selected amino acids with 'X'.