Using FuzDB


Upon clicking on the FC ID or the Protein name you can get to the expanded entry page.

Upon clicking on the FCxxx identifier or the Protein name you can get to the expanded entry page.

The core of FuzDB is the Browse module. Data in the Table of Entries provides basic information about the assembly, including the specification of the partners and the annotation of the fuzzy region(s). All fuzzy complexes have an identifier in the format of FCxxxx, and the same protein can be involved in multiple entries. The protein name also includes domain specifications and abbreviations.

ID: Identification of the complex. Each complex has a separate ID.
Protein name:The name of the protein containing the fuzzy region.
Uniprot ID:Uniprot ID of the protein with the fuzzy region, which is linked to the sequence in fasta format.
If the sequence is a chimera and does not correspond to the Uniprot sequence,
it is explicitly given in the expanded entry page.
Organism:Organism of the protein with a fuzzy region.
Partner:Interacting partner for the fuzzy protein.
Detection method:Experimental techniques, which were used to demonstrate the fuzziness of the complex.
PDB code: Protein Data Bank code(s) if the structure is available (linked to PDB).
BMRB code: Biological Magnetic Resonance Data Bank identification (linked to BMRB).
Class: Topological classification of the complex (P-polymorphic, C-clamp, F-flanking, R-random).
linked to the Classes module.
Fuzzy region: Sequence coordinates of the fuzzy regions (based on the Uniprot sequence).
Reference: PubMed ID(s) of the papers describing fuzziness of the complex, further references
can be found in the expanded entry page.

Upon clicking on the FC ID or the Protein name you can get to the expanded entry page.

Expanded entry page

Biological function: The function of the protein and the specific protein complex.
Domain organization/
sequence features
Topological organization of the protein, with special focus on intrinsically
disordered regions. The sequence of chimeras are given.
Structural evidence: Structural data demonstrating the structural multiplicity in the complex.
Biochemical evidence: Biochemical data demonstrating the impact of the conformationally heterogeneous region on function.
Structure/mechanism: Detailed structural description and mechanism of the complex.
Mechanism category: Mechanistic category of the complex (conformational selection, flexibility modulation,
competitive binding, tethering)
The role of PTMs in regulating the activity of the complex.
Isoforms, context-
Different isoforms, generated by alternative splicing affecting the fuzzy region.
Context-specific features of isoforms.
Significance: The relationship between the fuzziness of the complex and its function.
Further reading: Additional references.

Only those fields are displayed, where relevant information is available.


Simple text search

The simple text surveys all sections of the Table of Entries and the Expanded Entry. Unlike the advanced search it cannot be limited to specific columns or fields. This option is useful for example to list fuzzy complexes with specific functions or from a set of species (e.g. yeasts). A simple text search is an efficient way to look for expressions that are located in the descriptive sections of the Expanded Entry page.  For example, applying the “unfolding” filter will select proteins that unfold or expand upon binding to their partners. to find entries in the database.

Advanced search

The advanced search option is to look for terms in specific sections, such as protein or partner name, the PDB or BMRB code, or PubMed ID. The user may also search for fuzzy complexes which have been determined by a given experimental technique, as listed in the Methods module. It is possible to use a combination of specific fields, such as topology and mechanism. For example, applying “flanking” (topology) and “tethering” (mechanism) filters will select those fuzzy regions which flank ordered binding sites and serve to anchor them to their partners.

Both searches are case insensitive. The results could be downloaded in text format using Text view option in the menu.


The Methods module collects the experimental techniques, which have been applied to study fuzzy assemblies. Methods is linked to the Detection method column of the Table of Entries in the Browse module and can also appear as a pop-up window.


The Classes module describes the topological and mechanistic categories of fuzzy complexes. This is linked to the Class column of the Table of Entries in the Browse module and can also appear as a pop-up window.


The Upload module is for submission of new entries to the database. This module is highly protected, with the user requiring a safety key to upload data, which can be obtained by email. The process of submission is described in detail step-by-step and the data will be validated. By providing an email address, the user receives an electronic code that enables him/her to submit data. The required fields are the name of the protein and partner(s) and either the structural or the biochemical evidence, although for a new FuzDB entry both types of data will be required. The user is advised to provide a reference, such as a PubMed or a structure identifier. Specifying the sequence of the protein is recommended, but is not obligatory. An automatic email is generated upon submission to notify the FuzDB team. In most cases, the authors are contacted for missing or ambiguous information and an extensive literature search is performed to complement data. Obviously, email inquiries regarding fuzzy complex candidates are also considered. The contact name and email of the submitter is displayed in the Expended Entry page.


The Analysis module provides examples for analysis and interpretation of data for individual systems and for comparative analysis of fuzzy complexes.