Evidence Codes for the Gene Ontology (GO)

This table presents the evidence codes used by the Gene Ontology^TM Consortium, with examples of the types of experiments, data, or statements that are included by each code. The evidence code is linked with a specific GO annotation and literature reference to describe what type of evidence was present in that reference to make the annotation. Additional information about the GO Evidence Codes is available in documentation on the GO site, in GO Evidence Codes.

Code Definition Examples
IC Inferred By Curator
Used when an annotation is not supported by any evidence, but can be reasonably inferred by a curator from other GO annotations for which evidence is available.
IDA Inferred from Direct Assay
Enzyme assays
In vitro reconstitution
Immunofluorescence
Cell fractionation
Physical interaction/binding assay
IEA Inferred from Electronic Annotation
For annotations not reviewed by a curator, including
"Matches" in sequence similarity comparisons
Transferred from database records
Keyword mapping files
IEP Inferred from Expression Pattern
Transcript levels [e.g. Northerns, microarray data]
Protein levels [e.g. Western blots]
IGC Inferred from Genomic Context
operon structure
syntenic regions
pathway analysis
genome scale analysis of processes
IGI Inferred from Genetic Interaction
Traditional genetic interactions such as suppressors, synthetic lethals, etc.
Functional complementation
Rescue experiments
Inference about one gene drawn from the mutation of a different gene
IMP Inferred from Mutant Phenotype
mutations, natural or introduced
polymorphism or allelic variation
altering the expression, including RNAi, anti-sense RNAs, antibody depletion, etc.
overexpression/ectopic expression
IPI Inferred from Physical Interaction
2-hybrid interactions
Co-purification
Co-immunoprecipitation
Ion/protein binding experiments
ISA Inferred from Sequence Alignment
Used when the primary piece of evidence is a pairwise or multiple sequence alignment
ISM Inferred from Sequence Model
Used when any kind of sequence modeling method (e.g. Hidden Markov Models) is the primary piece of evidence
ISO Inferred from Sequence Orthology
Used when the assertion of orthology between the gene product and an experimentally characterized gene product in another organism is the main basis of the annotation
ISS Inferred from Sequence or structural Similarity
Parent evidence code for annotations based on sequence or structural similarity based methods
When possible one of the more specific codes (ISA, ISO, or ISM) should be used.
NAS Non-traceable Author Statement
Database entries that do not cite a paper [e.g. SwissProt records, YPD protein reports]
Statements in papers [abstract, introduction, or discussion] that a curator cannot trace to another publication
ND No Biological Data Available
Used for annotations when information about the molecular function, biological process, or cellular component of the gene or gene product being annotated is not available.
RCA Reviewed Computational Analysis
Predictions based on computational analyses of large-scale experimental data sets
Predictions based on computational analyses that integrate datasets of several types
TAS Traceable Author Statement
Any statement in an article where the original evidence (experimental results, sequence comparison, etc.) is not directly shown, but is referenced in the article and therefore can be traced to another source.

Code	Definition	Examples
IC	Inferred By Curator	Used when an annotation is not supported by any evidence, but can be reasonably inferred by a curator from other GO annotations for which evidence is available.
IDA	Inferred from Direct Assay	Enzyme assays In vitro reconstitution Immunofluorescence Cell fractionation Physical interaction/binding assay
IEA	Inferred from Electronic Annotation	For annotations not reviewed by a curator, including "Matches" in sequence similarity comparisons Transferred from database records Keyword mapping files
IEP	Inferred from Expression Pattern	Transcript levels [e.g. Northerns, microarray data] Protein levels [e.g. Western blots]
IGC	Inferred from Genomic Context	operon structure syntenic regions pathway analysis genome scale analysis of processes
IGI	Inferred from Genetic Interaction	Traditional genetic interactions such as suppressors, synthetic lethals, etc. Functional complementation Rescue experiments Inference about one gene drawn from the mutation of a different gene
IMP	Inferred from Mutant Phenotype	mutations, natural or introduced polymorphism or allelic variation altering the expression, including RNAi, anti-sense RNAs, antibody depletion, etc. overexpression/ectopic expression
IPI	Inferred from Physical Interaction	2-hybrid interactions Co-purification Co-immunoprecipitation Ion/protein binding experiments
ISA	Inferred from Sequence Alignment	Used when the primary piece of evidence is a pairwise or multiple sequence alignment
ISM	Inferred from Sequence Model	Used when any kind of sequence modeling method (e.g. Hidden Markov Models) is the primary piece of evidence
ISO	Inferred from Sequence Orthology	Used when the assertion of orthology between the gene product and an experimentally characterized gene product in another organism is the main basis of the annotation
ISS	Inferred from Sequence or structural Similarity	Parent evidence code for annotations based on sequence or structural similarity based methods When possible one of the more specific codes (ISA, ISO, or ISM) should be used.
NAS	Non-traceable Author Statement	Database entries that do not cite a paper [e.g. SwissProt records, YPD protein reports] Statements in papers [abstract, introduction, or discussion] that a curator cannot trace to another publication
ND	No Biological Data Available	Used for annotations when information about the molecular function, biological process, or cellular component of the gene or gene product being annotated is not available.
RCA	Reviewed Computational Analysis	Predictions based on computational analyses of large-scale experimental data sets Predictions based on computational analyses that integrate datasets of several types
TAS	Traceable Author Statement	Any statement in an article where the original evidence (experimental results, sequence comparison, etc.) is not directly shown, but is referenced in the article and therefore can be traced to another source.

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