Biomaterial Database

A comparison of scoring functions for protein sequence profile alignment. 2004

Robert C Edgar, and Kimmen Sjölander

bob@drive5.com

BACKGROUND In recent years, several methods have been proposed for aligning two protein sequence profiles, with reported improvements in alignment accuracy and homolog discrimination versus sequence-sequence methods (e.g. BLAST) and profile-sequence methods (e.g. PSI-BLAST). Profile-profile alignment is also the iterated step in progressive multiple sequence alignment algorithms such as CLUSTALW. However, little is known about the relative performance of different profile-profile scoring functions. In this work, we evaluate the alignment accuracy of 23 different profile-profile scoring functions by comparing alignments of 488 pairs of sequences with identity < or =30% against structural alignments. We optimize parameters for all scoring functions on the same training set and use profiles of alignments from both PSI-BLAST and SAM-T99. Structural alignments are constructed from a consensus between the FSSP database and CE structural aligner. We compare the results with sequence-sequence and sequence-profile methods, including BLAST and PSI-BLAST. RESULTS We find that profile-profile alignment gives an average improvement over our test set of typically 2-3% over profile-sequence alignment and approximately 40% over sequence-sequence alignment. No statistically significant difference is seen in the relative performance of most of the scoring functions tested. Significantly better results are obtained with profiles constructed from SAM-T99 alignments than from PSI-BLAST alignments. BACKGROUND Source code, reference alignments and more detailed results are freely available at http://phylogenomics.berkeley.edu/profilealignment/

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D000465	Algorithms	A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.	Algorithm
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D012680	Sensitivity and Specificity	Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)	Specificity,Sensitivity,Specificity and Sensitivity
D015203	Reproducibility of Results	The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.	Reliability and Validity,Reliability of Result,Reproducibility Of Result,Reproducibility of Finding,Validity of Result,Validity of Results,Face Validity,Reliability (Epidemiology),Reliability of Results,Reproducibility of Findings,Test-Retest Reliability,Validity (Epidemiology),Finding Reproducibilities,Finding Reproducibility,Of Result, Reproducibility,Of Results, Reproducibility,Reliabilities, Test-Retest,Reliability, Test-Retest,Result Reliabilities,Result Reliability,Result Validities,Result Validity,Result, Reproducibility Of,Results, Reproducibility Of,Test Retest Reliability,Validity and Reliability,Validity, Face
D016415	Sequence Alignment	The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.	Sequence Homology Determination,Determination, Sequence Homology,Alignment, Sequence,Alignments, Sequence,Determinations, Sequence Homology,Sequence Alignments,Sequence Homology Determinations
D017386	Sequence Homology, Amino Acid	The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.	Homologous Sequences, Amino Acid,Amino Acid Sequence Homology,Homologs, Amino Acid Sequence,Homologs, Protein Sequence,Homology, Protein Sequence,Protein Sequence Homologs,Protein Sequence Homology,Sequence Homology, Protein,Homolog, Protein Sequence,Homologies, Protein Sequence,Protein Sequence Homolog,Protein Sequence Homologies,Sequence Homolog, Protein,Sequence Homologies, Protein,Sequence Homologs, Protein
D020539	Sequence Analysis, Protein	A process that includes the determination of AMINO ACID SEQUENCE of a protein (or peptide, oligopeptide or peptide fragment) and the information analysis of the sequence.	Amino Acid Sequence Analysis,Peptide Sequence Analysis,Protein Sequence Analysis,Sequence Determination, Protein,Amino Acid Sequence Analyses,Amino Acid Sequence Determination,Amino Acid Sequence Determinations,Amino Acid Sequencing,Peptide Sequence Determination,Protein Sequencing,Sequence Analyses, Amino Acid,Sequence Analysis, Amino Acid,Sequence Analysis, Peptide,Sequence Determination, Amino Acid,Sequence Determinations, Amino Acid,Acid Sequencing, Amino,Analyses, Peptide Sequence,Analyses, Protein Sequence,Analysis, Peptide Sequence,Analysis, Protein Sequence,Peptide Sequence Analyses,Peptide Sequence Determinations,Protein Sequence Analyses,Protein Sequence Determination,Protein Sequence Determinations,Sequence Analyses, Peptide,Sequence Analyses, Protein,Sequence Determination, Peptide,Sequence Determinations, Peptide,Sequence Determinations, Protein,Sequencing, Amino Acid,Sequencing, Protein
D020869	Gene Expression Profiling	The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell.	Gene Expression Analysis,Gene Expression Pattern Analysis,Transcript Expression Analysis,Transcriptome Profiling,Transcriptomics,mRNA Differential Display,Gene Expression Monitoring,Transcriptome Analysis,Analyses, Gene Expression,Analyses, Transcript Expression,Analyses, Transcriptome,Analysis, Gene Expression,Analysis, Transcript Expression,Analysis, Transcriptome,Differential Display, mRNA,Differential Displays, mRNA,Expression Analyses, Gene,Expression Analysis, Gene,Gene Expression Analyses,Gene Expression Monitorings,Gene Expression Profilings,Monitoring, Gene Expression,Monitorings, Gene Expression,Profiling, Gene Expression,Profiling, Transcriptome,Profilings, Gene Expression,Profilings, Transcriptome,Transcript Expression Analyses,Transcriptome Analyses,Transcriptome Profilings,mRNA Differential Displays