UniProt release 10.3

Complete set of Arabidopsis thaliana F-box proteins

F-box proteins play a major role in the ubiquitin conjugation pathway. There are involved in the third step of this pathway. Most of the F-box protein contains a conserved F-box domain near the N-terminus and a variable region. The F-box domain can interact with Cullin and one of the SKP1 proteins to form a E3 SCF (SKP1/Cullin/F-box) ubiquitin ligase complex. The variable region interacts with a specific protein, which is, in turn, ubiquitinated and thus targeted to protein degradation. This variable region confers the specificity of the SCF complex.

The whole set of Arabidopsis thaliana, more than 630 F-box protein sequences, has been manually reviewed and integrated into UniProtKB/Swiss-Prot. About 120 wrong gene model predictions have been corrected, including 26 F-box proteins obtained by splitting erroneous gene predictions covering more than one gene. This represents one of the largest protein family of a given species that had ever been integrated into UniProtKB/Swiss-Prot.

In A. thaliana, almost half of F-box proteins contains a combination of different domains which is used to define subgroups:

›300	FB	F-box alone
91	FBL	F-box associated with LRR-repeat
124	FBK	F-box associated with Kelch-repeat
30	FBD	F-box associated with FBD
41	FDL	F-box associated with FBD and LRR-repeat
4	FBLK	F-box associated with LRR-repeat and Kelch-repeat

Among this large protein family, less than 30 members have been characterized: their functions are various and include flowering, circadian cycle, hormone signaling, and plant defense.

Related entries:

• a F-box protein involved in flowering (Q39090, UFO_ARATH)
• a F-box protein involved in circadian cycle (Q94BT6, ADO1_ARATH)
• a F-box protein involved in hormone signaling (Q570C0, TIR1_ARATH)
• a F-box protein involved in plant defense a F-box protein involved in plant defense (O04197, COI1_ARATH)
• Cullin (Q94AH6, CUL1_ARATH)
• SKP1A (Q39255, SKP1A_ARATH)
• Ubiquitin (P59263, UBIQ_ARATH)