F-box

F-box
Identifiers
Symbol	?

The F-box is a protein domain of approximately 40-50 amino acids that functions in protein-protein interactions. It was first identified in the protein Cyclin F, which is involved in the regulation of the cell cycle. The F-box domain is a crucial component of the SCF complex (Skp1-Cullin-F-box protein complex), which is a type of ubiquitin ligase complex.

Structure

The F-box domain typically consists of a conserved sequence of amino acids that form a structural motif capable of binding to other proteins. This domain is often found at the N-terminus of proteins and is responsible for the interaction with the Skp1 protein, which is a part of the SCF complex.

Function

The primary function of the F-box domain is to mediate protein-protein interactions, particularly in the context of the SCF complex. The SCF complex is involved in the process of ubiquitination, where it tags proteins for degradation by the proteasome. The F-box protein acts as a substrate receptor, recognizing and binding to specific target proteins that need to be ubiquitinated.

Types of F-box Proteins

F-box proteins can be classified into three main categories based on the presence of additional protein interaction domains:

• FBXW (F-box and WD40 domain proteins)
• FBXL (F-box and leucine-rich repeat proteins)
• FBXO (F-box only proteins)

Role in Disease

Mutations or dysregulation of F-box proteins have been implicated in various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases. For example, the F-box protein FBXW7 is known to act as a tumor suppressor, and its loss of function can lead to uncontrolled cell proliferation.

Related Pages

• Ubiquitin ligase
• Proteasome
• SCF complex
• Cyclin F
• Skp1
• Cullin

See Also

• Protein domain
• Ubiquitination
• Cell cycle