Entity Relationship (ER) diagram representing the data structure used for the construction of CoryneRegNet. The ER was implemented in the DBMS MySQL and is divided into two main parts: the generalized data structure (GDS) and the ontology-based data structure. Rectangles represent entities, rhombi represent relations between two entities and circles represent attributes of entities. The entities Concept and Relation, which are the main components of the ontology-based data structure, are located in the center of the ER diagram. They store all essential data on genes, proteins and functional modules as well as every linkage between them. They are typed (Concept_class and Relation_type) and link to the controlled vocabulary (CV) they have been extracted from. Furthermore, they link to their generalized attributes (GDS_relation and GDS_concept) and to associated sequences (entity Sequence). Alternative names and accessions are stored in the tables of the entities Concept_name and Concept_accession.