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Protein

Bcl-2-like protein 1

Gene

Bcl2l1

Organism
Mus musculus (Mouse)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Potent inhibitor of cell death. Inhibits activation of caspases. Appears to regulate cell death by blocking the voltage-dependent anion channel (VDAC) by binding to it and preventing the release of the caspase activator, CYC1, from the mitochondrial membrane. Also acts as a regulator of G2 checkpoint and progression to cytokinesis during mitosis.1 Publication
Isoform Bcl-X(L) also regulates presynaptic plasticity, including neurotransmitter release and recovery, number of axonal mitochondria as well as size and number of synaptic vesicle clusters. During synaptic stimulation, increases ATP availability from mitochondria through regulation of mitochondrial membrane ATP synthase F1F0 activity and regulates endocytic vesicle retrieval in hippocampal neurons through association with DMN1L and stimulation of its GTPase activity in synaptic vesicles (By similarity). May attenuate inflammation impairing NLRP1-inflammasome activation, hence CASP1 activation and IL1B release (By similarity).By similarity
Isoform Bcl-X(S) promotes apoptosis.By similarity

GO - Molecular functioni

GO - Biological processi

  • apoptotic process in bone marrow Source: MGI
  • cell proliferation Source: MGI
  • cellular process regulating host cell cycle in response to virus Source: MGI
  • cellular response to alkaloid Source: MGI
  • cellular response to amino acid stimulus Source: MGI
  • cellular response to gamma radiation Source: MGI
  • cytokinesis Source: UniProtKB
  • extrinsic apoptotic signaling pathway in absence of ligand Source: MGI
  • fertilization Source: MGI
  • germ cell development Source: MGI
  • growth Source: MGI
  • hepatocyte apoptotic process Source: MGI
  • intrinsic apoptotic signaling pathway in response to DNA damage Source: MGI
  • in utero embryonic development Source: MGI
  • male gonad development Source: MGI
  • mitochondrion morphogenesis Source: MGI
  • mitotic cell cycle checkpoint Source: UniProtKB
  • negative regulation of apoptotic process Source: MGI
  • negative regulation of establishment of protein localization to plasma membrane Source: MGI
  • negative regulation of execution phase of apoptosis Source: UniProtKB
  • negative regulation of intrinsic apoptotic signaling pathway Source: MGI
  • negative regulation of intrinsic apoptotic signaling pathway in response to DNA damage Source: MGI
  • negative regulation of neuron apoptotic process Source: MGI
  • neuron apoptotic process Source: MGI
  • ovarian follicle development Source: MGI
  • positive regulation of apoptotic process Source: MGI
  • positive regulation of cell proliferation Source: MGI
  • regulation of mitochondrial membrane permeability Source: MGI
  • regulation of mitochondrial membrane potential Source: MGI
  • release of cytochrome c from mitochondria Source: MGI
  • response to cycloheximide Source: MGI
  • response to cytokine Source: MGI
  • response to radiation Source: MGI
  • response to virus Source: MGI
  • spermatogenesis Source: MGI
  • suppression by virus of host apoptotic process Source: MGI
Complete GO annotation...

Keywords - Biological processi

Apoptosis

Enzyme and pathway databases

ReactomeiR-MMU-111453. BH3-only proteins associate with and inactivate anti-apoptotic BCL-2 members.
R-MMU-844455. The NLRP1 inflammasome.

Names & Taxonomyi

Protein namesi
Recommended name:
Bcl-2-like protein 1
Short name:
Bcl2-L-1
Alternative name(s):
Apoptosis regulator Bcl-X
Gene namesi
Name:Bcl2l1
Synonyms:Bcl2l, Bclx
OrganismiMus musculus (Mouse)
Taxonomic identifieri10090 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresRodentiaSciurognathiMuroideaMuridaeMurinaeMusMus
Proteomesi
  • UP000000589 Componenti: Chromosome 2

Organism-specific databases

MGIiMGI:88139. Bcl2l1.

Subcellular locationi

Isoform Bcl-X(L) :

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Transmembranei210 – 226HelicalSequence analysisAdd BLAST17

GO - Cellular componenti

  • Bcl-2 family protein complex Source: MGI
  • cell junction Source: UniProtKB-KW
  • centrosome Source: UniProtKB
  • cytoplasm Source: MGI
  • cytosol Source: MGI
  • integral component of membrane Source: UniProtKB-KW
  • intracellular Source: MGI
  • mitochondrial inner membrane Source: UniProtKB-SubCell
  • mitochondrial matrix Source: UniProtKB-SubCell
  • mitochondrial membrane Source: MGI
  • mitochondrial outer membrane Source: MGI
  • mitochondrion Source: MGI
  • nuclear membrane Source: UniProtKB-SubCell
  • synaptic vesicle membrane Source: UniProtKB-SubCell
Complete GO annotation...

Keywords - Cellular componenti

Cell junction, Cytoplasm, Cytoplasmic vesicle, Cytoskeleton, Membrane, Mitochondrion, Mitochondrion inner membrane, Mitochondrion outer membrane, Nucleus, Synapse

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00001430631 – 233Bcl-2-like protein 1Add BLAST233

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei49Phosphoserine; by PLK3By similarity1
Modified residuei62Phosphoserine; by CDK1By similarity1

Post-translational modificationi

Proteolytically cleaved by caspases during apoptosis. The cleaved protein, lacking the BH4 motif, has pro-apoptotic activity.By similarity
Phosphorylated on Ser-62 by CDK1. This phosphorylation is partial in normal mitotic cells, but complete in G2-arrested cells upon DNA-damage, thus promoting subsequent apoptosis probably by triggering caspases-mediated proteolysis. Phosphorylated by PLK3, leading to regulate the G2 checkpoint and progression to cytokinesis during mitosis. Phosphorylation at Ser-49 appears during the S phase and G2, disappears rapidly in early mitosis during prometaphase, metaphase and early anaphase, and re-appears during telophase and cytokinesis (By similarity).By similarity

Keywords - PTMi

Phosphoprotein

Proteomic databases

PaxDbiQ64373.
PRIDEiQ64373.

PTM databases

iPTMnetiQ64373.
PhosphoSitePlusiQ64373.

Miscellaneous databases

PMAP-CutDBQ64373.

Expressioni

Tissue specificityi

Widely expressed, with highest levels in the brain, thymus, bone marrow, and kidney. Bcl-X(L) and Bcl-X(delta-TM) expression is enhanced in B- and T-lymphocytes that have been activated.1 Publication

Developmental stagei

Bcl-X(beta) is expressed in both embryonal and postnatal tissues, whereas Bcl-X(L) is predominantly found in postnatal tissues.1 Publication

Gene expression databases

BgeeiENSMUSG00000007659.
CleanExiMM_BCL2L1.
ExpressionAtlasiQ64373. baseline and differential.
GenevisibleiQ64373. MM.

Interactioni

Subunit structurei

Homodimer. Isoform Bcl-X(L) forms heterodimers with BAX, BAK or BCL2. Heterodimerization with BAX does not seem to be required for anti-apoptotic activity. Interacts with BAD. Interacts (isoform Bcl-X(L)) with SIVA1 (isoform 1); the interaction inhibits the anti-apoptotic activity. Interacts with BECN1 and PGAM5. Isoform Bcl-X(L) interacts with IKZF3. Interacts with HEBP2. Isoform Bcl-X(L) interacts with BOP. Interacts with p53/TP53 and BBC3; interaction with BBC3 disrupts the interaction with p53/TP53. Isoform Bcl-X(L) interacts with DNM1L and CLTA; DNM1L and BCL2L1 isoform BCL-X(L) may form a complex in synaptic vesicles that also contains clathrin and MFF. Interacts with ATP5A and ATP5B; the interactions mediate the association of isoform Bcl-X(L) with the mitochondrial membrane ATP synthase F1F0 ATP synthase (By similarity). Interacts with VDAC1 (By similarity). Isoform Bcl-X(L) interacts (via the loop between motifs BH4 and BH3) with NLRP1 (via LRR repeats), but not with NLRP2, NLRP3, NLRP4, PYCARD, nor MEFV. Interacts with BCL2L11 (via BH3) (PubMed:27013495, PubMed:14499110).By similarity2 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
BadQ613372EBI-526380,EBI-400328

GO - Molecular functioni

Protein-protein interaction databases

BioGridi198323. 8 interactors.
IntActiQ64373. 8 interactors.
MINTiMINT-87027.
STRINGi10090.ENSMUSP00000007803.

Chemistry databases

BindingDBiQ64373.

Structurei

Secondary structure

1233
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Helixi1 – 20Combined sources20
Helixi24 – 27Combined sources4
Helixi83 – 101Combined sources19
Helixi102 – 105Combined sources4
Helixi106 – 112Combined sources7
Turni116 – 118Combined sources3
Helixi120 – 127Combined sources8
Helixi128 – 131Combined sources4
Helixi137 – 156Combined sources20
Helixi162 – 177Combined sources16
Helixi179 – 184Combined sources6
Helixi187 – 195Combined sources9

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PQ0X-ray2.20A1-196[»]
1PQ1X-ray1.65A1-196[»]
2BZWX-ray2.30A1-211[»]
3IHCX-ray1.85A1-196[»]
3IHDX-ray1.88A1-196[»]
3IHEX-ray3.00A1-196[»]
3IHFX-ray2.28A/B/C/D1-196[»]
3IIGX-ray2.30A1-196[»]
3IIHX-ray2.75A1-196[»]
3ILBX-ray2.38A/N1-196[»]
3ILCX-ray1.64A1-196[»]
4YJ4X-ray2.10A1-196[»]
4YK9X-ray1.70A/F2-196[»]
5C3GX-ray2.45A1-26[»]
ProteinModelPortaliQ64373.
SMRiQ64373.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiQ64373.

Family & Domainsi

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi4 – 24BH4Add BLAST21
Motifi86 – 100BH3Add BLAST15
Motifi129 – 148BH1Add BLAST20
Motifi180 – 195BH2Add BLAST16

Domaini

The BH4 motif is required for anti-apoptotic activity. The BH1 and BH2 motifs are required for both heterodimerization with other Bcl-2 family members and for repression of cell death.
The loop between motifs BH4 and BH3 is required for the interaction with NLRP1.By similarity

Sequence similaritiesi

Belongs to the Bcl-2 family.Curated

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG4728. Eukaryota.
ENOG41123S0. LUCA.
GeneTreeiENSGT00530000062935.
HOGENOMiHOG000056452.
InParanoidiQ64373.
KOiK04570.
OMAiNGSPSWH.
OrthoDBiEOG091G0OCU.
TreeFamiTF315834.

Family and domain databases

InterProiIPR013279. Apop_reg_BclX.
IPR002475. Bcl2-like.
IPR004725. Bcl2/BclX.
IPR020717. Bcl2_BH1_motif_CS.
IPR020726. Bcl2_BH2_motif_CS.
IPR020728. Bcl2_BH3_motif_CS.
IPR003093. Bcl2_BH4.
IPR020731. Bcl2_BH4_motif_CS.
IPR026298. Blc2_fam.
[Graphical view]
PANTHERiPTHR11256. PTHR11256. 1 hit.
PTHR11256:SF12. PTHR11256:SF12. 1 hit.
PfamiPF00452. Bcl-2. 1 hit.
PF02180. BH4. 1 hit.
[Graphical view]
PRINTSiPR01864. APOPREGBCLX.
PR01862. BCL2FAMILY.
SMARTiSM00265. BH4. 1 hit.
[Graphical view]
TIGRFAMsiTIGR00865. bcl-2. 1 hit.
PROSITEiPS50062. BCL2_FAMILY. 1 hit.
PS01080. BH1. 1 hit.
PS01258. BH2. 1 hit.
PS01259. BH3. 1 hit.
PS01260. BH4_1. 1 hit.
PS50063. BH4_2. 1 hit.
[Graphical view]

Sequences (4)i

Sequence statusi: Complete.

This entry describes 4 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform Bcl-X(L) (identifier: Q64373-1) [UniParc]FASTAAdd to basket
Also known as: Bcl-xL

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

« Hide

        10         20         30         40         50
MSQSNRELVV DFLSYKLSQK GYSWSQFSDV EENRTEAPEE TEAERETPSA
60 70 80 90 100
INGNPSWHLA DSPAVNGATG HSSSLDAREV IPMAAVKQAL REAGDEFELR
110 120 130 140 150
YRRAFSDLTS QLHITPGTAY QSFEQVVNEL FRDGVNWGRI VAFFSFGGAL
160 170 180 190 200
CVESVDKEMQ VLVSRIASWM ATYLNDHLEP WIQENGGWDT FVDLYGNNAA
210 220 230
AESRKGQERF NRWFLTGMTV AGVVLLGSLF SRK
Length:233
Mass (Da):26,132
Last modified:November 1, 1996 - v1
Checksum:i24D2AC79887E072E
GO
Isoform Bcl-X(S) (identifier: Q64373-2) [UniParc]FASTAAdd to basket
Also known as: Bcl-xS

The sequence of this isoform differs from the canonical sequence as follows:
     126-188: Missing.

Show »
Length:170
Mass (Da):18,961
Checksum:i2C12D8EC7F735D52
GO
Isoform Bcl-X(beta) (identifier: Q64373-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     189-233: DTFVDLYGNNAAAESRKGQERFNRWFLTGMTVAGVVLLGSLFSRK → VRTTPLVCPPLACVSLLCEHP

Show »
Length:209
Mass (Da):23,357
Checksum:iDC53895D8014B5DD
GO
Isoform Bcl-X(delta-TM) (identifier: Q64373-4) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     194-233: LYGNNAAAESRKGQERFNRWFLTGMTVAGVVLLGSLFSRK → GHDCGWCGSAGLTLQSEVTRH

Show »
Length:214
Mass (Da):23,900
Checksum:i4FAECDC42B064B4A
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti207 – 209QER → KEG in AAC53459 (PubMed:9390687).Curated3

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_000517126 – 188Missing in isoform Bcl-X(S). CuratedAdd BLAST63
Alternative sequenceiVSP_000518189 – 233DTFVD…LFSRK → VRTTPLVCPPLACVSLLCEH P in isoform Bcl-X(beta). CuratedAdd BLAST45
Alternative sequenceiVSP_000519194 – 233LYGNN…LFSRK → GHDCGWCGSAGLTLQSEVTR H in isoform Bcl-X(delta-TM). CuratedAdd BLAST40

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X83574 mRNA. Translation: CAA58557.1.
L35049 mRNA. Translation: AAA51039.1.
L35048 mRNA. Translation: AAA51040.1.
U10102 mRNA. Translation: AAA82174.1.
U10101 mRNA. Translation: AAA82173.1.
U10100 mRNA. Translation: AAA82172.1.
U51278 mRNA. Translation: AAC53459.1.
U51279 mRNA. Translation: AAC53460.1.
U78031, U78030 Genomic DNA. Translation: AAB96881.1.
CCDSiCCDS16899.1. [Q64373-1]
PIRiI49055.
I49056.
I49057.
RefSeqiNP_001276645.1. NM_001289716.1. [Q64373-1]
NP_001276646.1. NM_001289717.1. [Q64373-1]
NP_033873.3. NM_009743.5. [Q64373-1]
XP_006498672.1. XM_006498609.3. [Q64373-1]
XP_006498674.1. XM_006498611.3. [Q64373-1]
XP_006498675.1. XM_006498612.2. [Q64373-1]
XP_011237562.1. XM_011239260.2. [Q64373-1]
UniGeneiMm.238213.

Genome annotation databases

EnsembliENSMUST00000007803; ENSMUSP00000007803; ENSMUSG00000007659. [Q64373-1]
ENSMUST00000109820; ENSMUSP00000105445; ENSMUSG00000007659. [Q64373-1]
ENSMUST00000134902; ENSMUSP00000134614; ENSMUSG00000007659. [Q64373-3]
ENSMUST00000140436; ENSMUSP00000134596; ENSMUSG00000007659. [Q64373-3]
GeneIDi12048.
KEGGimmu:12048.
UCSCiuc008ngi.2. mouse. [Q64373-2]
uc008ngj.2. mouse. [Q64373-1]
uc008ngn.2. mouse. [Q64373-3]

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X83574 mRNA. Translation: CAA58557.1.
L35049 mRNA. Translation: AAA51039.1.
L35048 mRNA. Translation: AAA51040.1.
U10102 mRNA. Translation: AAA82174.1.
U10101 mRNA. Translation: AAA82173.1.
U10100 mRNA. Translation: AAA82172.1.
U51278 mRNA. Translation: AAC53459.1.
U51279 mRNA. Translation: AAC53460.1.
U78031, U78030 Genomic DNA. Translation: AAB96881.1.
CCDSiCCDS16899.1. [Q64373-1]
PIRiI49055.
I49056.
I49057.
RefSeqiNP_001276645.1. NM_001289716.1. [Q64373-1]
NP_001276646.1. NM_001289717.1. [Q64373-1]
NP_033873.3. NM_009743.5. [Q64373-1]
XP_006498672.1. XM_006498609.3. [Q64373-1]
XP_006498674.1. XM_006498611.3. [Q64373-1]
XP_006498675.1. XM_006498612.2. [Q64373-1]
XP_011237562.1. XM_011239260.2. [Q64373-1]
UniGeneiMm.238213.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PQ0X-ray2.20A1-196[»]
1PQ1X-ray1.65A1-196[»]
2BZWX-ray2.30A1-211[»]
3IHCX-ray1.85A1-196[»]
3IHDX-ray1.88A1-196[»]
3IHEX-ray3.00A1-196[»]
3IHFX-ray2.28A/B/C/D1-196[»]
3IIGX-ray2.30A1-196[»]
3IIHX-ray2.75A1-196[»]
3ILBX-ray2.38A/N1-196[»]
3ILCX-ray1.64A1-196[»]
4YJ4X-ray2.10A1-196[»]
4YK9X-ray1.70A/F2-196[»]
5C3GX-ray2.45A1-26[»]
ProteinModelPortaliQ64373.
SMRiQ64373.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi198323. 8 interactors.
IntActiQ64373. 8 interactors.
MINTiMINT-87027.
STRINGi10090.ENSMUSP00000007803.

Chemistry databases

BindingDBiQ64373.

PTM databases

iPTMnetiQ64373.
PhosphoSitePlusiQ64373.

Proteomic databases

PaxDbiQ64373.
PRIDEiQ64373.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENSMUST00000007803; ENSMUSP00000007803; ENSMUSG00000007659. [Q64373-1]
ENSMUST00000109820; ENSMUSP00000105445; ENSMUSG00000007659. [Q64373-1]
ENSMUST00000134902; ENSMUSP00000134614; ENSMUSG00000007659. [Q64373-3]
ENSMUST00000140436; ENSMUSP00000134596; ENSMUSG00000007659. [Q64373-3]
GeneIDi12048.
KEGGimmu:12048.
UCSCiuc008ngi.2. mouse. [Q64373-2]
uc008ngj.2. mouse. [Q64373-1]
uc008ngn.2. mouse. [Q64373-3]

Organism-specific databases

CTDi598.
MGIiMGI:88139. Bcl2l1.

Phylogenomic databases

eggNOGiKOG4728. Eukaryota.
ENOG41123S0. LUCA.
GeneTreeiENSGT00530000062935.
HOGENOMiHOG000056452.
InParanoidiQ64373.
KOiK04570.
OMAiNGSPSWH.
OrthoDBiEOG091G0OCU.
TreeFamiTF315834.

Enzyme and pathway databases

ReactomeiR-MMU-111453. BH3-only proteins associate with and inactivate anti-apoptotic BCL-2 members.
R-MMU-844455. The NLRP1 inflammasome.

Miscellaneous databases

EvolutionaryTraceiQ64373.
PMAP-CutDBQ64373.
PROiQ64373.
SOURCEiSearch...

Gene expression databases

BgeeiENSMUSG00000007659.
CleanExiMM_BCL2L1.
ExpressionAtlasiQ64373. baseline and differential.
GenevisibleiQ64373. MM.

Family and domain databases

InterProiIPR013279. Apop_reg_BclX.
IPR002475. Bcl2-like.
IPR004725. Bcl2/BclX.
IPR020717. Bcl2_BH1_motif_CS.
IPR020726. Bcl2_BH2_motif_CS.
IPR020728. Bcl2_BH3_motif_CS.
IPR003093. Bcl2_BH4.
IPR020731. Bcl2_BH4_motif_CS.
IPR026298. Blc2_fam.
[Graphical view]
PANTHERiPTHR11256. PTHR11256. 1 hit.
PTHR11256:SF12. PTHR11256:SF12. 1 hit.
PfamiPF00452. Bcl-2. 1 hit.
PF02180. BH4. 1 hit.
[Graphical view]
PRINTSiPR01864. APOPREGBCLX.
PR01862. BCL2FAMILY.
SMARTiSM00265. BH4. 1 hit.
[Graphical view]
TIGRFAMsiTIGR00865. bcl-2. 1 hit.
PROSITEiPS50062. BCL2_FAMILY. 1 hit.
PS01080. BH1. 1 hit.
PS01258. BH2. 1 hit.
PS01259. BH3. 1 hit.
PS01260. BH4_1. 1 hit.
PS50063. BH4_2. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiB2CL1_MOUSE
AccessioniPrimary (citable) accession number: Q64373
Secondary accession number(s): O35844
, Q60657, Q60658, Q61338
Entry historyi
Integrated into UniProtKB/Swiss-Prot: November 1, 1997
Last sequence update: November 1, 1996
Last modified: November 30, 2016
This is version 167 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

3D-structure, Complete proteome, Reference proteome

Documents

  1. MGD cross-references
    Mouse Genome Database (MGD) cross-references in UniProtKB/Swiss-Prot
  2. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  3. SIMILARITY comments
    Index of protein domains and families

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.