The F-box protein family

Table 2 F-box proteins that function in SCF complexes

F-box protein	Organism	Substrates	Mutant phenotype
Cdc4	S. cerevisiae	Sic1 and Far1 - CDK inhibitors	G1 cell-cycle arrest
		Cdc6 - DNA replication factor
		Gcn4 - transcription factor
Met30	S. cerevisiae	Met4 - transcription factor	G1 cell-cycle arrest
		Swe1 - cell cycle kinase
Grr1	S. cerevisiae	Cln1 and Cln2 - G1 cyclins	Defective glucose signaling
		Gic2 - cytoskeleton regulator
Pop1	S. pombe	Rum1 - CDK inhibitor	Polyploidy
		Cdc18 - DNA replication factor
Pop2/Sud1	S. pombe	Rum1 - CDK inhibitor	Polyploidy
		Cdc18 - DNA replication factor
Scon2^*	N. crassa	?	Defective sulfur response
SconB^*	A. nidulans	?	Defective sulfur response
TIR1	A. thaliana	?	Defective auxin response
COI1^*	A. thaliana	?	Defective jasmonite response
LIN-23^*	C. elegans	?	Hyperplasia
SEL-10^*	C. elegans	LIN-12 - cell surface receptor	Basically wild type
Slimb^*	D. melanogaster	Armadillo - adhesion and signaling	Centrosome over-replication and mutant clones induce
		Cubitus Interruptus - transcription factor	ectopic limbs in surrounding tissue
ß-TrCP	H. sapiens	ß-catenin - adhesion and signaling
		I?Ba - transcription inhibitor	?
		CD4 - cell surface receptor (when cells are infected by HIV)
ß-TrCP2/HOS	H. sapiens	ß-catenin - adhesion and signaling	?
		I?Ba - transcription inhibitor
SKP2	H. sapiens /	cyclin E- G1 cyclin (free, not bound by CDK2)	Small mice with some polyploid tissues and centrosome
	M. musculus	p27^KIP1 - CDK inhibitor	over-replication

^*F-box proteins that have not been experimentally demonstrated to function in SCF complexes, but each are orthologs of known SCF proteins in other organisms and so are likely to function in SCF complexes. Two other plant F-box proteins, UFO and FIM, are required for flower development in Arabidopsis thaliana and Antirrhinum majus, respectively [32,33]. Although both of these F-box proteins bind to Skp1 proteins, it is unclear whether they function in SCF complexes or bind Skp1 for other purposes, as is the case for Ctf13. Additional potential substrates that have not been conclusively documented are not listed. References can be obtained from [10], with the exception of the more recent references for LIN-23 [34], centrosome over-replication in Slimb mutants [35], and the substrates Met4 [36], Gcn4 [37], cyclin E [38], and p27^KIP1 [25,38,39,40]. Species included in the table are Saccharomyces cerevisiae, Schizosaccharomyces pombe, Neurospora crassa, Aspergillus nidulans, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens and Mus musculus.

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