GenAnnotation

Genannotation refers to the process of assigning meaningful biological information to genome sequences by identifying and characterizing the functional elements they contain. It encompasses both structural annotation—such as locating genes, exons, introns, untranslated regions, noncoding RNAs, and regulatory elements—and functional annotation, which assigns roles, products, and relationships to those elements, including names, enzyme activities, pathways, domains, and ontologies.

Structural annotation aims to delineate gene models and transcript structures. It relies on evidence from ab initio gene prediction, homology to annotated genes in other species, and experimental data such as RNA sequencing and proteomics. Functional annotation uses sequence similarity, conserved domains, gene ontology terms, and curated databases to infer gene products, biochemical functions, cellular processes, and interactions.

The typical workflow starts with a genome assembly, followed by structural annotation to define gene boundaries and transcripts. Functional annotation then assigns putative functions and integrates data from homologous genes, domain analyses, and external resources. Annotation pipelines often combine automated prediction with manual curation and community input. Outputs are usually stored in public databases and integrated into genome browsers to support researchers in comparative genomics and experimental planning.

Common tools and resources include gene prediction programs (for example, AUGUSTUS, GeneMark, or MAKER), similarity search and domain analysis tools (BLAST, InterProScan), and reference databases (Gene Ontology, UniProt, Pfam). Accurate genannotation is essential for understanding gene structure, function, evolution, and their roles in health and disease, although it remains challenging due to repetitive sequences, alternative splicing, and limited experimental evidence for many species.