F-box protein
Encyclopedia
F-box proteins are protein
s containing at least one F-box domain. The first identified F-box protein is one of three components of the SCF complex
, which mediates ubiquitin
ation of proteins targeted for degradation by the proteasome
.
F-box proteins have also been associated with cellular functions such as signal transduction
and regulation of the cell cycle
. In plants, many F-box proteins are represented in gene networks broadly regulated by microRNA-mediated gene silencing
via RNA interference
.
In human cells, in high-iron condition, two iron atoms stabilise the F-Box FBXL5
and then the complexe mediates the ubiquitination of IRP2.
The F-box domain is a protein
structural motif
of about 50 amino acid
s that mediates protein–protein interactions. It was first identified in cyclin F.
The F-box motif interacts directly with the SCF protein Skp1
, and F-box domains commonly exist in proteins in concert with other protein–protein interaction motifs such as leucine-rich repeat
s and WD repeats, which are thought to mediate interactions with SCF substrates.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s containing at least one F-box domain. The first identified F-box protein is one of three components of the SCF complex
SCF complex
Skp, Cullin, F-box containing complex is a multi-protein E3 ubiquitin ligase complex catalyzing the ubiquitination of proteins destined for proteasomal degradation...
, which mediates ubiquitin
Ubiquitin
Ubiquitin is a small regulatory protein that has been found in almost all tissues of eukaryotic organisms. Among other functions, it directs protein recycling.Ubiquitin can be attached to proteins and label them for destruction...
ation of proteins targeted for degradation by the proteasome
Proteasome
Proteasomes are very large protein complexes inside all eukaryotes and archaea, and in some bacteria. In eukaryotes, they are located in the nucleus and the cytoplasm. The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks...
.
F-box proteins have also been associated with cellular functions such as signal transduction
Signal transduction
Signal transduction occurs when an extracellular signaling molecule activates a cell surface receptor. In turn, this receptor alters intracellular molecules creating a response...
and regulation of the cell cycle
Cell cycle
The cell cycle, or cell-division cycle, is the series of events that takes place in a cell leading to its division and duplication . In cells without a nucleus , the cell cycle occurs via a process termed binary fission...
. In plants, many F-box proteins are represented in gene networks broadly regulated by microRNA-mediated gene silencing
Gene silencing
Gene silencing is a general term describing epigenetic processes of gene regulation. The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic modification...
via RNA interference
RNA interference
RNA interference is a process within living cells that moderates the activity of their genes. Historically, it was known by other names, including co-suppression, post transcriptional gene silencing , and quelling. Only after these apparently unrelated processes were fully understood did it become...
.
In human cells, in high-iron condition, two iron atoms stabilise the F-Box FBXL5
FBXL5
F-box/LRR-repeat protein 5 is a protein that in humans is encoded by the FBXL5 gene.FBXL5 is an iron sensor. It promotes IRP2 ubiquitination and then its degradation.-Further reading:...
and then the complexe mediates the ubiquitination of IRP2.
The F-box domain is a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
structural motif
Structural motif
In a chain-like biological molecule, such as a protein or nucleic acid, a structural motif is a supersecondary structure, which appears also in a variety of other molecules...
of about 50 amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s that mediates protein–protein interactions. It was first identified in cyclin F.
The F-box motif interacts directly with the SCF protein Skp1
SKP1A
S-phase kinase-associated protein 1 is an enzyme that in humans is encoded by the SKP1 gene.This gene encodes a protein that is a member of the SCF ubiquitin ligase protein complex. It binds to F-box proteins , such as cyclin F, S-phase kinase-associated protein 2, and other regulatory proteins...
, and F-box domains commonly exist in proteins in concert with other protein–protein interaction motifs such as leucine-rich repeat
Leucine-rich repeat
A leucine-rich repeat is a protein structural motif that forms an α/β horseshoe fold. It is composed of repeating 20–30 amino acid stretches that are unusually rich in the hydrophobic amino acid leucine...
s and WD repeats, which are thought to mediate interactions with SCF substrates.