MMDB: 3D structure data in Entrez

Three-dimensional structures are now known for roughly half of all protein families. It is thus quite likely, in searching sequence databases, that on e will encounter a homolog with known structure and be able to use this inf ormation to infer structure-function properties. The goal of Entrez's 3D st ructure database is to make this information accessible and useful to molec ular biologists, To this end, Entrez's search engine provides three powerfu l features: (i) Links between databases; one may search by term matching in Medline(R), for example, and link to 3D structures reported in these artic les, (ii) Sequence and structure neighbors; one may select all sequences si milar to one of interest, for example, and link to any known 3D structures, (iii) Sequence and structure visualization; identifying a homolog with kno wn structure, one may view a combined molecular-graphic and alignment displ ay, to infer approximate 3D structure. Entrez's MMDB (Molecular Modeling Da taBase) may be accessed at: http://www.ncbi.nlm.nih.gov/Entrez/structure.ht ml.