F-box only protein 3 (FBXO3) is a substrate recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex that mediates the ubiquitination of transcription factor coactivators such as HIPK2 and EP300, leading to their rapid degradation by the proteasome []. FBX03 interacts with a nuclear protein PML, which stabilises the transcription factor complex by protecting HIPK2 and p300 from SCFFbx3-induced degradation until transcription is completed []. PML, HIPK2 and FBXO3 may act synergically to activate p53/TP53-dependent transactivation [].
This domain is found in the yeast cell wall assembly regulator Smi1 (also known as Knr4) [, ]. Saccharomyces cerevisiae Knr4 has a regulatory role in chitin deposition and in cell wall assembly []. It is believed to connect the PKC1-SLT2 MAPK pathway with cell proliferation. It has been shown to interact with Bck2, a gene involved in cell cycle progression in S. cerevisiae (forming a complex) to allow PKC1 to coordinate the cell cycle (cell proliferation) with cell wall integrity [, ]. Knr4 also interacts with the tyrosine-tRNA synthetase protein encoded by Tys1 and is involved in sporulation process []. Proteins containing this domain also include the animal F-box only protein 3 (FBXO3). In humans, FBXO3 is a substrate recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex [].Interestingly, Smi1/Knr4 homologues from bacteria are potential immunity proteins in a subset of these contact-dependent inhibitory toxin systems [].Note: previously reported evidence that Knr4 may interact with nuclear matrix-association region []may be due to an artefact [].
This domain superfamily is found in the yeast cell wall assembly regulator Smi1 (also known as Knr4) [, ]. Saccharomyces cerevisiae Knr4 has a regulatory role in chitin deposition and in cell wall assembly []. It is believed to connect the PKC1-SLT2 MAPK pathway with cell proliferation. It has been shown to interact with Bck2, a gene involved in cell cycle progression in S. cerevisiae (forming a complex) to allow PKC1 to coordinate the cell cycle (cell proliferation) with cell wall integrity [, ]. Knr4 also interacts with the tyrosine-tRNA synthetase protein encoded by Tys1 and is involved in sporulation process []. Proteins containing this domain also include the animal F-box only protein 3 (FBXO3). In humans, FBXO3 is a substrate recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex [].Interestingly, Smi1/Knr4 homologues from bacteria are potential immunity proteins in a subset of these contact-dependent inhibitory toxin systems [, ].Note: previously reported evidence that Knr4 may interact with nuclear matrix-association region []may be due to an artefact [].This domain superfamily is also found in the Syd protein which interacts with the SecY protein.
