F-box domain found in F-box only protein 5 (FBXO5) and similar proteins; FBXO5, also called FBX5, or early mitotic inhibitor 1 (EMI1), acts as a regulator that inhibits the anaphase-promoting complex/cyclosome (APC/C), which controls cell cycle progression through the sequential degradation of various substrates from S phase to early mitosis. During mitotic cell cycle, it plays a role as both substrate and inhibitor of the APC-FZR1 complex. During G1 phase, it plays a role as substrate of the APC-FZR1 complex E3 ligase. The F-box domain has a role in mediating protein-protein interactions in a variety of contexts, such as polyubiquitination, transcription elongation, centromere binding and translational repression.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 2022854637 223 AELFQKNLKHILANILRHLSDMDLINFAKVSTTWKKILQEDKWAFQIYS 271
Cdd:cd22170     1 AELFLRDLKHVLAKILRHLSDMDLINCSKVSTTWRKILQEDKWAFQIYS 49

F-box domain found in F-box only protein 5 (FBXO5) and similar proteins; FBXO5, also called FBX5, or early mitotic inhibitor 1 (EMI1), acts as a regulator that inhibits the anaphase-promoting complex/cyclosome (APC/C), which controls cell cycle progression through the sequential degradation of various substrates from S phase to early mitosis. During mitotic cell cycle, it plays a role as both substrate and inhibitor of the APC-FZR1 complex. During G1 phase, it plays a role as substrate of the APC-FZR1 complex E3 ligase. The F-box domain has a role in mediating protein-protein interactions in a variety of contexts, such as polyubiquitination, transcription elongation, centromere binding and translational repression.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 2022854637 223 AELFQKNLKHILANILRHLSDMDLINFAKVSTTWKKILQEDKWAFQIYS 271
Cdd:cd22170     1 AELFLRDLKHVLAKILRHLSDMDLINCSKVSTTWRKILQEDKWAFQIYS 49

A Receptor for Ubiquitination Targets;

                           10        20        30
                   ....*....|....*....|....*....|...
gi 2022854637  232 HILANILRHLSDMDLINFAKVSTTWKKILQEDK 264
Cdd:smart00256   4 EILEEILSKLDPKDLLRLRKVSRKWRSLIDSHD 36

F-box domain found in F-box only protein 5 (FBXO5) and similar proteins; FBXO5, also called FBX5, or early mitotic inhibitor 1 (EMI1), acts as a regulator that inhibits the anaphase-promoting complex/cyclosome (APC/C), which controls cell cycle progression through the sequential degradation of various substrates from S phase to early mitosis. During mitotic cell cycle, it plays a role as both substrate and inhibitor of the APC-FZR1 complex. During G1 phase, it plays a role as substrate of the APC-FZR1 complex E3 ligase. The F-box domain has a role in mediating protein-protein interactions in a variety of contexts, such as polyubiquitination, transcription elongation, centromere binding and translational repression.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 2022854637 223 AELFQKNLKHILANILRHLSDMDLINFAKVSTTWKKILQEDKWAFQIYS 271
Cdd:cd22170     1 AELFLRDLKHVLAKILRHLSDMDLINCSKVSTTWRKILQEDKWAFQIYS 49

BRcat domain found in F-box only protein 43 (FBXO43); FBXO43, also called FBX43 or endogenous meiotic inhibitor 2 (EMI2), plays a key role during the meiotic cell cycle. It is required to establish and maintain the arrest of oocytes at the second meiotic metaphase until fertilization. It probably acts by inhibiting the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. It may recognize and bind to some phosphorylated proteins and promotes their ubiquitination and degradation. FBXO43 contains an F-box domain, and the first half of the RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the BRcat (benign-catalytic) domain that adopts the same fold as the Rcat domain while lacking the catalytic cysteine residue and ubiquitination activity.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 2022854637 341 ESLKVCHRCGSPAKYDSYLQRATCNREGCGFDFCTRCMCCYHSSSDCVSG 390
Cdd:cd20365     2 EALKPCPRCQSPAKYQPVKKRGLCSREACGFDFCVLCLCAFHGSKECTSG 51

F-box domain found in F-box only protein 43 (FBXO43) and similar proteins; FBXO43, also called FBX43, or endogenous meiotic inhibitor 2 (EMI2), plays a key role during the meiotic cell cycle. It is required to establish and maintain the arrest of oocytes at the second meiotic metaphase until fertilization. It probably acts by inhibiting the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. It may recognize and bind to some phosphorylated proteins and promote their ubiquitination and degradation. The F-box domain has a role in mediating protein-protein interactions in a variety of contexts, such as polyubiquitination, transcription elongation, centromere binding and translational repression.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 2022854637 223 AELFQKNLKHILANILRHLSDMDLINFAKVSTTWKKILQEDKWAFQ 268
Cdd:cd22171     1 AELKNRNLKHILAIILDLLTAESICSFWKVSKNWRDIIVQDKSAYQ 46

BRcat domain found in the RING finger protein 19 (RNF19) subfamily; This subfamily includes RING finger protein RNF19A and RNF19B, both of which are transmembrane (TM) domain-containing RBR-type E3 ubiquitin-protein ligases. RNF19A, also called double ring-finger protein (Dorfin), or p38, localizes to the ubiquitylated inclusions in Parkinson's disease (PD), dementia with Lewy bodies (LBs), multiple system atrophy, and amyotrophic lateral sclerosis (ALS). It interacts with Psmc3, a protein component of the 19S regulatory cap of the 26S proteasome, and further participates in the ubiquitin-proteasome system in acrosome biogenesis, spermatid head shaping, and development of the head-tail coupling apparatus and tail. It modulates the ubiquitination and degradation of Calcium-sensing receptor (CaR), which may contribute to a general mechanism for CaR quality control during biosynthesis. Moreover, RNF19A can also ubiquitylate mutant superoxide dismutase 1 (SOD1), the causative gene of familial ALS. It may associate with the endoplasmic reticulum-associated degradation (ERAD) pathway, which is related to the pathogenesis of neurodegenerative disorders, such as PD or Alzheimer's disease. It is also involved in the pathogenic process of PD and LB formation by ubiquitylation of synphilin-1. RNF19B, also called IBR domain-containing protein 3 or natural killer (NK) lytic-associated molecule (NKLAM), plays a role in controlling tumor dissemination and metastasis. It is involved in the cytolytic function of NK cells and cytotoxic T lymphocytes (CTLs). It interacts with ubiquitin conjugates UbcH7 and UbcH8, and ubiquitinates uridine kinase like-1 (URKL-1) protein, targeting it for degradation. Moreover, RNF19B is a novel component of macrophage phagosomes and plays a role in macrophage anti-bacterial activity. It functions as a novel modulator of macrophage inducible nitric oxide synthase (iNOS) expression. Both RNF19A and RNF19B contain an RBR domain followed by three TMs. The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the BRcat domain of the RNF19 subfamily that adopts the same fold as the Rcat domain while lacking the catalytic cysteine residue and ubiquitination activity.

                          10        20
                  ....*....|....*....|....*..
gi 2022854637 361 RATCNREGCGFDFCTRCMCCYHSSSDC 387
Cdd:cd20338    42 KLTCQRPGCGTEFCYHCKQPWHPNQTC 68

F-box domain superfamily; This short domain is commonly found at the N-terminus of various proteins, and typically co-occurs with one or more other conserved domains or motifs, such as leucine rich repeats, WD40 repeats, kelch, tub, spry, and others. The F-box domain has a role in mediating protein-protein interactions in a variety of contexts, such as polyubiquitination, transcription elongation, centromere binding and translational repression. One of the best researched roles of F-box proteins is their participation in SCF (Skp1-Cul1-F-box protein), a multi-protein complex that functions as a ubiquitin E3 ligase, where the role of the F-box protein is to recruit target substrates. Gene families containing the F-box are found greatly expanded in narrow taxonomic lineages, such as flowering plants and nematodes. In this hierarchical classification, many of the subfamilies are named according to their domain architectures.

                          10        20        30
                  ....*....|....*....|....*....|
gi 2022854637 232 HILANILRHLSDMDLINFAKVSTTWKKILQ 261
Cdd:cd09917     6 EILLKILSYLDPRDLLRLSLVCKRWRELAS 35