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| Cn3D | |
|---|---|
| Name | Cn3D |
| Developer | National Center for Biotechnology Information |
| Initial release | 1998 |
| Latest release | 4.3.1 |
| Operating system | Windows, macOS, Linux |
| Genre | Molecular graphics |
| License | Public domain / NIH |
Cn3D
Cn3D is a molecular structure and sequence visualization application developed by the National Center for Biotechnology Information for interactive inspection of three-dimensional biomolecular structures and sequence alignments. It integrates structural data from the Protein Data Bank, sequence annotations from GenBank, and cross-references from resources such as PubMed, enabling researchers to inspect relationships among structures, sequences, and literature. The application has been used in conjunction with resources like BLAST, Entrez, and the Conserved Domain Database to facilitate structure-guided sequence analysis.
Cn3D provides an interactive environment combining macromolecular visualization, sequence alignment display, and annotation browsing. It displays coordinates from entries in the Protein Data Bank, aligns sequences in the context of annotations drawn from Conserved Domain Database and Pfam, and links to literature in PubMed and records in GenBank. The program interoperates with tools and databases such as BLAST, Entrez Gene, UniProt, Swiss-Prot, and RCSB PDB, enabling cross-referencing across institutions like the National Institutes of Health and collaborations with projects including NCBI Reference Sequences and the International Nucleotide Sequence Database Collaboration.
Cn3D supports synchronized views of three-dimensional structures and corresponding multiple sequence alignments, rendering cartoon representations similar to tools like PyMOL and Chimera. It offers coloring schemes tied to annotations from databases such as Pfam, SMART, and the Conserved Domain Database, and facilitates domain identification akin to workflows used with HMMER and MAFFT. Interactive features include residue selection that reflects in both structural view and alignment panels, export functions compatible with PDBx/mmCIF and traditional PDB formats, and printing/export routines for figures intended for publications in journals such as Nature and Science. Cn3D integrates with sequence search outputs from BLASTp, PSI-BLAST, and other NCBI tools, and supports visualization conventions shared with community resources like ModBase, Swiss-Model, and CATH.
Development began at the National Center for Biotechnology Information in the late 1990s to provide an NCBI-native viewer for structure results returned by services such as BLAST. Early releases coincided with milestones at the Protein Data Bank and community efforts exemplified by the Human Genome Project and the expansion of structural genomics initiatives including Structural Genomics Consortium. Over successive versions, Cn3D incorporated features influenced by contemporaneous software such as RasMol and MolScript, adopted file compatibility standards reflecting recommendations from the Worldwide Protein Data Bank and engaged with metadata practices from GenBank and RefSeq. Maintenance and updates have been coordinated via NCBI engineering teams and affiliated collaborators at institutions like the National Library of Medicine.
Cn3D reads coordinate files in legacy PDB format and in newer PDBx/mmCIF representations, while aligning sequences derived from GenBank and RefSeq entries. It consumes annotation files generated by resources such as the Conserved Domain Database, Pfam, and SMART, and exports images and coordinate subsets compatible with visualization pipelines used by PyMOL, ChimeraX, and Jmol. Integration with NCBI's Entrez system allows Cn3D to pull cross-referenced accession records, literature citations from PubMed Central and PubMed, and taxonomy data from the NCBI Taxonomy database. The software supports annotation mapping conventions parallel to those in UniProtKB and structural classification schemes like SCOP and CATH.
Cn3D has been used in structural biology workflows for interpreting homology models from Swiss-Model and ModBase, inspecting ligand interactions alongside data from ChEMBL and BindingDB, and teaching structural concepts in courses that reference textbooks and curricula at institutions such as Harvard University and Massachusetts Institute of Technology. Researchers employ Cn3D in combination with sequence analysis pipelines involving BLAST, HMMER, and multiple sequence alignment tools like Clustal Omega and MAFFT to annotate functional sites, map disease-associated variants curated in resources like ClinVar, and explore evolutionary relationships documented in Tree of Life projects. It has been used to prepare figures for publication in outlets including Cell, PNAS, and Nature Structural & Molecular Biology.
Cn3D has been recognized for enabling transparent linkage between sequence alignments and three-dimensional context, complementing visualization ecosystems that include PyMOL, UCSF Chimera, and Jmol. Its integration with the National Center for Biotechnology Information suite has made it a practical choice for users already working within NCBI services, and it has played a role in educational initiatives and community resources maintained by organizations such as the Protein Data Bank in Europe and the Research Collaboratory for Structural Bioinformatics. While alternative viewers have gained popularity for advanced rendering and scripting—examples include VMD and ChimeraX—Cn3D's niche remains its tight coupling to NCBI databases and its facilitation of structure-informed sequence interpretation used by researchers at institutions like the Broad Institute and facilities such as the European Molecular Biology Laboratory.
Category:Bioinformatics software Category:Molecular graphics software Category:National Center for Biotechnology Information