RING finger (Really Interesting New Gene) domain and U-box domain superfamily; The RING finger is a specialized type of Zn-finger of 40 to 60 residues that binds two atoms of zinc. It is defined by the "cross-brace" motif that chelates zinc atoms by eight amino acid residues, typically Cys or His, arranged in a characteristic spacing. Canonical RING motifs have been categorized into two major subclasses, RING-HC (C3HC4-type) and RING-H2 (C3H2C3-type), according to their Cys/His content. There are also many variants of RING fingers: some have different Cys/His patterns while some lack a single Cys or His residue at typical Zn ligand positions (the fourth or eighth zinc ligand is prevalently exchanged for an Asp, which can indeed chelate Zn in a RING finger as well). C4C4-, C3HC3D-, C2H2C4-, and C3HC5-type RING fingers are closely related to RING-HC fingers. In contrast, C4HC3- (RING-CH alias RINGv), C3H3C2-, C3H2C2D-, C3DHC3-, and C4HC2H-type RING fingers are more closely related to RING-H2 fingers. However, not all RING finger-containing proteins display regular RING finger features, and the RING finger family has turned out to be multifarious. The degenerate RING fingers of the Siz/PIAS RING (SP-RING) family proteins and sporulation protein RMD5, are characterized by lacking the second, fifth, and sixth Zn2+ ion-coordinating residues. They bind only one Zn2+ ion. On the other hand, the RING fingers of the human APC11 and RBX1 proteins can bind a third Zn atom since they harbor four additional Zn ligands. U-box is a modified form of the RING finger domain that lacks metal chelating Cys and His residues. It resembles the cross-brace RING structure consisting of three beta-sheets and a single alpha-helix, which would be stabilized by salt bridges instead of chelated metal ions. U-box proteins are widely distributed among eukaryotic organisms and show a higher prevalence in plants than in other organisms. RING finger/U-box-containing proteins are a group of diverse proteins with a variety of cellular functions, including oncogenesis, development, viral replication, signal transduction, the cell cycle and apoptosis. Many of them are ubiquitin-protein ligases (E3s) that serve as scaffolds for binding to ubiquitin-conjugating enzymes (E2s, also referred to as ubiquitin carrier proteins or UBCs) in close proximity to substrate proteins, which enable efficient transfer of ubiquitin from E2 to the substrates.

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                 ....*....|....*....|....*....|....*....|....
gi 767987520 660 KQCVACRERAHGAVLRPCQHHILCEPCAATAPECPYCKGQPLQW 703
Cdd:cd16772    1 KKCIVCQERDRSIVLQPCQHYVLCEHCAASKPECPYCKTKILKW 44

Zinc finger C-x8-C-x5-C-x3-H type (and similar);

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                  ....*....|....*....|....*..
gi 767987520  306 YKSTKCNDMRQTGYCPRGPFCAFAHVE 332
Cdd:pfam00642   1 YKTELCRFFLRTGYCKYGDRCKFAHGQ 27

RING finger, HC subclass, found in RING finger protein unkempt-like (UNKL) and similar proteins; UNKL, also known as zinc finger CCCH domain-containing protein 5-like, is a putative E3 ubiquitin-protein ligase that may participate in a protein complex showing an E3 ligase activity regulated by RAC1. It shows high sequence similarity with RING finger protein unkempt (UNK), which is a metazoan-specific zinc finger protein enriched in embryonic brains, and may play a broad regulatory role during the formation of the central nervous system (CNS). UNKL contains several CCCH-type zinc fingers at the N-terminus, and a C3HC4-type RING-HC finger at its C-terminus.

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                 ....*....|....*....|....*....|....*....|....
gi 767987520 660 KQCVACRERAHGAVLRPCQHHILCEPCAATAPECPYCKGQPLQW 703
Cdd:cd16772    1 KKCIVCQERDRSIVLQPCQHYVLCEHCAASKPECPYCKTKILKW 44

Zinc finger, C3HC4 type (RING finger);

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                  ....*....|....*....|....*....|....*....|..
gi 767987520  660 KQCVACRERAHGAVLRPCQHHILCEPCA----ATAPECPYCK 697
Cdd:pfam13920   3 LLCVICLDRPRNVVLLPCGHLCLCEECAerllRKKKKCPICR 44

Uncharacterized conserved protein, contains a C-terminal ATPase domain [Function unknown];

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 767987520  589 ELARVRRQLDEAKRKIRQWEESWQQVKQVCDAWQREAQEAKERARVADS---DRQLALQKKEEVEAQVIFQLRAKQ 661
Cdd:COG4913   700 ELEELEEELDELKGEIGRLEKELEQAEEELDELQDRLEAAEDLARLELRallEERFAAALGDAVERELRENLEERI 775

RING finger, HC subclass, found in RING finger protein unkempt-like (UNKL) and similar proteins; UNKL, also known as zinc finger CCCH domain-containing protein 5-like, is a putative E3 ubiquitin-protein ligase that may participate in a protein complex showing an E3 ligase activity regulated by RAC1. It shows high sequence similarity with RING finger protein unkempt (UNK), which is a metazoan-specific zinc finger protein enriched in embryonic brains, and may play a broad regulatory role during the formation of the central nervous system (CNS). UNKL contains several CCCH-type zinc fingers at the N-terminus, and a C3HC4-type RING-HC finger at its C-terminus.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 767987520 660 KQCVACRERAHGAVLRPCQHHILCEPCAATAPECPYCKGQPLQW 703
Cdd:cd16772    1 KKCIVCQERDRSIVLQPCQHYVLCEHCAASKPECPYCKTKILKW 44

RING finger, HC subclass, found in RING finger protein unkempt (UNK), unkempt-like (UNKL), and similar proteins; UNK, also known as zinc finger CCCH domain-containing protein 5, is a metazoan-specific zinc finger protein enriched in embryonic brains. It may play a broad regulatory role during the formation of the central nervous system (CNS). It is a sequence-specific RNA-binding protein required for early neuronal morphology. UNK is a neurogenic component of the mTOR pathway, and functions as a negative regulator of the timing of photoreceptor differentiation. It also specifically binds to Brg/Brm-associated factor BAF60b and promotes its ubiquitination in a Rac1-dependent manner. UNKL, also known as zinc finger CCCH domain-containing protein 5-like, is a putative E3 ubiquitin-protein ligase that may participate in a protein complex showing an E3 ligase activity regulated by RAC1. Both UNK and UNKL contain several tandem CCCH-type zinc fingers at the N-terminus, and a C3HC4-type RING-HC finger at its C-terminus.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 767987520 660 KQCVACRERAHGAVLRPCQHHILCEPCAATAPECPYCK 697
Cdd:cd16614    1 KKCMKCEERNRSVAVLPCQHYVLCEQCAETATECPYCH 38

RING finger, HC subclass, found in leucine-rich repeat and sterile alpha motif-containing protein 1 (LRSAM1) and similar proteins; LRSAM1, also known as Tsg101-associated ligase (TAL), or RIFLE, is an E3 ubiquitin-protein ligase that physically associates with, and selectively ubiquitylates, Tsg101, an E2-like molecule that regulates vesicular trafficking processes in yeast and mammals. It regulates a Tsg101-associated complex responsible for the sorting of cargo into cytoplasm-containing vesicles that bud at the multivesicular body and at the plasma membrane. LRSAM1 is a multidomain protein containing an N-terminal leucine-rich repeat (LRR), followed by several recognizable motifs, including an ezrin-radixin-moezin (ERM) domain, a coiled-coil (CC) region, a SAM domain, and a C-terminal C3HC4-type RING-HC finger domain.

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                 ....*....|....*....|....*....|....*...
gi 767987520 662 CVACRERAHGAVLRPCQHHILCEPCAATAPECPYCKGQ 699
Cdd:cd16515    4 CVVCMDAESQVIFLPCGHVCCCQTCSSSLSTCPLCRAD 41

RING finger, HC subclass, found in RING finger protein unkempt (UNK) and similar proteins; UNK, also known as zinc finger CCCH domain-containing protein 5, is a metazoan-specific zinc finger protein enriched in embryonic brains. It may play a broad regulatory role during the formation of the central nervous system (CNS). It is a sequence-specific RNA-binding protein required for early neuronal morphology. UNK is a neurogenic component of the mTOR pathway, and functions as a negative regulator of the timing of photoreceptor differentiation. It also specifically binds to Brg/Brm-associated factor BAF60b and promotes its ubiquitination in a Rac1-dependent manner. UNK contains six tandem CCCH-type zinc fingers at the N-terminus, and a C3HC4-type RING-HC finger at its C-terminus.

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                 ....*....|....*....|....*....|....*
gi 767987520 662 CVACRERahGAVLRPCQHHILCEPCaATAPECPYC 696
Cdd:cd16771    5 CLKCQEL--KRVTLPCQHALLCETC-ATSEECPIC 36

Trichohyalin-plectin-homology domain; This family is a mixtrue of two different families of eukaryotic proteins. Trichoplein or mitostatin, was first defined as a meiosis-specific nuclear structural protein. It has since been linked with mitochondrial movement. It is associated with the mitochondrial outer membrane, and over-expression leads to reduction in mitochondrial motility whereas lack of it enhances mitochondrial movement. The activity appears to be mediated through binding the mitochondria to the actin intermediate filaments (IFs). The family is in the trichohyalin-plectin-homology domain.

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                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767987520  589 ELARVRRQLDEAKRKIRQWEESWQqvkqvcDAWQrEAQEAKERARvadsDRQLALQKKEEV-------EAQVIFQLRAKQ 661
Cdd:pfam13868 185 EIARLRAQQEKAQDEKAERDELRA------KLYQ-EEQERKERQK----EREEAEKKARQRqelqqarEEQIELKERRLA 253

                  ....*...
gi 767987520  662 CVACRERA 669
Cdd:pfam13868 254 EEAEREEE 261

Uncharacterized protein, contains DUF3084 domain [Function unknown];

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                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 767987520 589 ELARVRRQLDEAKRKIRQWEESWQQVKQVCDAWQREAQEAKERARVADSD-------RQLALQKKEEVEAQV 653
Cdd:COG4372   67 ELEQARSELEQLEEELEELNEQLQAAQAELAQAQEELESLQEEAEELQEEleelqkeRQDLEQQRKQLEAQI 138

RING finger, HC subclass, found in RNA-binding protein MEX3C; MEX3C, also known as RING finger and KH domain-containing protein 2 (RKHD2), or RING finger protein 194 (RNF194), is an RNA-binding phosphoprotein that acts as a suppressor of chromosomal instability. It functions as an ubiquitin E3 ligase responsible for the post-transcriptional, HLA-A allotype-specific regulation of MHC class I molecules (MHC-I). It also modifies retinoic acid inducible gene-1 (RIG-I) in stress granules and plays a critical role in eliciting antiviral immune responses. Moreover, MEX3C plays an essential role in normal postnatal growth via enhancing the local expression of insulin-like growth factor 1 (IGF1) in bone. It may also be involved in metabolic regulation of energy balance. MEX3C contains two K homology (KH) domains that provide RNA-binding capacity, and a C-terminal C3HC4-type RING-HC finger. Like other MEX-3 family proteins, MEX3C shuttles between the nucleus and the cytoplasm via the CRM1-dependent export pathway.

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                 ....*....|....*....|....*....|....*....|....*....
gi 767987520 662 CVACRERAHGAVLRPCQHHILCEPCA-----ATAPECPYCKG---QPLQ 702
Cdd:cd16722    4 CVICFENEVIAALVPCGHNLFCMECAnkiceKETPSCPVCQTavtQAIQ 52

RING finger, HC subclass, found in RNA-binding protein MEX3A; MEX3A, also known as RING finger and KH domain-containing protein 4 (RKHD4), is an RNA-binding phosphoprotein that localizes in P-bodies and stress granules, which are two structures involved in the storage and turnover of mRNAs. It has been implicated in the regulation of tumorigenesis. It controls the polarity and stemness of intestinal epithelial cells through the post-transcriptional regulation of the homeobox transcription factor CDX2, which plays a crucial role in intestinal cell fate specification, both during normal development and in tumorigenic processes involving intestinal reprogramming. Moreover, it exhibits a transforming activity when overexpressed in gastric epithelial cells. MEX3A contains two K homology (KH) domains that provide RNA-binding capacity, and a C-terminal C3HC4-type RING-HC finger. Like other MEX-3 family proteins, MEX3A shuttles between the nucleus and the cytoplasm via the CRM1-dependent export pathway.

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                 ....*....|....*....|....*....|....*....|...
gi 767987520 659 AKQCVACRERAHGAVLRPCQHHILCEPCAA-----TAPECPYC 696
Cdd:cd16720    2 GRDCMVCFESEVTAALVPCGHNLFCMECAVricerNEPECPVC 44

RING finger, HC subclass, found in E3 ubiquitin-protein ligase XIAP, baculoviral IAP repeat-containing protein 8 (BIRC8) and similar proteins; XIAP, also known as baculoviral IAP repeat-containing protein 4 (BIRC4), IAP-like protein (ILP), inhibitor of apoptosis protein 3 (IAP-3), or X-linked inhibitor of apoptosis protein (X-linked IAP), is a potent suppressor of apoptosis that directly inhibits specific members of the caspase family of cysteine proteases, including caspase-3, -7, and -9. It promotes proteasomal degradation of caspase-3 and enhances its anti-apoptotic effect in Fas-induced cell death. The ubiquitin-protein ligase (E3) activity of XIAP also exhibits in the ubiquitination of second mitochondria-derived activator of caspases (Smac). The mitochondrial proteins, Smac/DIABLO and Omi/HtrA2, can inhibit the antiapoptotic activity of XIAP. XIAP has also been implicated in several intracellular signaling cascades involved in the cellular response to stress, such as the c-Jun N-terminal kinase (JNK), the nuclear factor-kappaB (NF-kappaB), and the transforming growth factor-beta (TGF-beta) pathways. Moreover, XIAP can regulate copper homeostasis by interacting with MURR1. BIRC8, also known as inhibitor of apoptosis-like protein 2, IAP-like protein 2, ILP-2, or testis-specific inhibitor of apoptosis, is a tissue-specific homolog of E3 ubiquitin-protein ligase XIAP. It has been implicated in the control of apoptosis in the testis by direct inhibition of caspase 9. Both XIAP and BIRC8 contain three N-terminal baculoviral IAP repeat (BIR) domains, a ubiquitin-association (UBA) domain and a C3HC4-type RING-HC finger at the carboxyl terminus.

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                 ....*....|....*....|....*....|....*....
gi 767987520 658 RAKQCVACRERAHGAVLRPCQHHILCEPCAATAPECPYC 696
Cdd:cd16714   13 EEKLCKICMDRNISIVFIPCGHLVTCKQCAEALDKCPIC 51