Skip Header

You are using a version of browser that may not display all the features of this website. Please consider upgrading your browser.
Protein

Protein kinase C alpha type

Gene

Prkca

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

Functioni

Calcium-activated, phospholipid- and diacylglycerol (DAG)-dependent serine/threonine-protein kinase that is involved in positive and negative regulation of cell proliferation, apoptosis, differentiation, migration and adhesion, cardiac hypertrophy, angiogenesis, platelet function and inflammation, by directly phosphorylating targets such as RAF1, BCL2, CSPG4, TNNT2/CTNT, or activating signaling cascades involving MAPK1/3 (ERK1/2) and RAP1GAP. Depending on the cell type, is involved in cell proliferation and cell growth arrest by positive and negative regulation of the cell cycle. Can promote cell growth by phosphorylating and activating RAF1, which mediates the activation of the MAPK/ERK signaling cascade, and/or by up-regulating CDKN1A, which facilitates active cyclin-dependent kinase (CDK) complex formation. In cells stimulated by the phorbol ester PMA, can trigger a cell cycle arrest program which is associated with the accumulation of the hyper-phosphorylated growth-suppressive form of RB1 and induction of the CDK inhibitors CDKN1A and CDKN1B. Depending on the cell type, exhibits anti-apoptotic function and protects cells from apoptosis by suppressing the p53/TP53-mediated activation of IGFBP3, or mediates anti-apoptotic action by phosphorylating BCL2. During macrophage differentiation induced by macrophage colony-stimulating factor (CSF1), is translocated to the nucleus and is associated with macrophage development. After wounding, translocates from focal contacts to lamellipodia and participates in the modulation of desmosomal adhesion. Plays a role in cell motility by phosphorylating CSPG4, which induces association of CSPG4 with extensive lamellipodia at the cell periphery and polarization of the cell accompanied by increases in cell motility. Negatively regulates myocardial contractility and positively regulates angiogenesis, platelet aggregation and thrombus formation in arteries. Mediates hypertrophic growth of neonatal cardiomyocytes, in part through a MAPK1/3 (ERK1/2)-dependent signaling pathway, and upon PMA treatment, is required to induce cardiomyocyte hypertrophy up to heart failure and death, by increasing protein synthesis, protein-DNA ratio and cell surface area. Regulates cardiomyocyte function by phosphorylating cardiac troponin T (TNNT2/CTNT), which induces significant reduction in actomyosin ATPase activity, myofilament calcium sensitivity and myocardial contractility. In angiogenesis, is required for full endothelial cell migration, adhesion to vitronectin (VTN), and vascular endothelial growth factor A (VEGFA)-dependent regulation of kinase activation and vascular tube formation. Involved in the stabilization of VEGFA mRNA at post-transcriptional level and mediates VEGFA-induced cell proliferation. In the regulation of calcium-induced platelet aggregation, mediates signals from the CD36/GP4 receptor for granule release, and activates the integrin heterodimer ITGA2B-ITGB3 through the RAP1GAP pathway for adhesion. During response to lipopolysaccharides (LPS), may regulate selective LPS-induced macrophage functions involved in host defense and inflammation. But in some inflammatory responses, may negatively regulate NF-kappa-B-induced genes, through IL1A-dependent induction of NF-kappa-B inhibitor alpha (NFKBIA/IKBA). Upon stimulation with 12-O-tetradecanoylphorbol-13-acetate (TPA), phosphorylates EIF4G1, which modulates EIF4G1 binding to MKNK1 and may be involved in the regulation of EIF4E phosphorylation. Phosphorylates KIT, leading to inhibition of KIT activity. Phosphorylates ATF2 which promotes cooperation between ATF2 and JUN, activating transcription.3 Publications

Catalytic activityi

ATP + a protein = ADP + a phosphoprotein.

Cofactori

Ca2+By similarityNote: Binds 3 Ca2+ ions per subunit. The ions are bound to the C2 domain.By similarity

Enzyme regulationi

Classical (or conventional) PKCs (PRKCA, PRKCB and PRKCG) are activated by calcium and diacylglycerol (DAG) in the presence of phosphatidylserine. Three specific sites; Thr-497 (activation loop of the kinase domain), Thr-638 (turn motif) and Ser-657 (hydrophobic region), need to be phosphorylated for its full activation.

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Metal bindingi186Calcium 1; via carbonyl oxygenBy similarity1
Metal bindingi187Calcium 1By similarity1
Metal bindingi187Calcium 2By similarity1
Metal bindingi193Calcium 2By similarity1
Binding sitei195Inositol phosphate groupBy similarity1
Binding sitei245Inositol phosphate groupBy similarity1
Metal bindingi246Calcium 1By similarity1
Metal bindingi246Calcium 2By similarity1
Metal bindingi247Calcium 2; via carbonyl oxygenBy similarity1
Metal bindingi248Calcium 1By similarity1
Metal bindingi248Calcium 2By similarity1
Metal bindingi248Calcium 3By similarity1
Metal bindingi252Calcium 3; via carbonyl oxygenBy similarity1
Metal bindingi254Calcium 1By similarity1
Metal bindingi254Calcium 3By similarity1
Binding sitei368ATPPROSITE-ProRule annotation1
Active sitei463Proton acceptorPROSITE-ProRule annotation1

Regions

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Zinc fingeri36 – 86Phorbol-ester/DAG-type 1PROSITE-ProRule annotationAdd BLAST51
Zinc fingeri101 – 151Phorbol-ester/DAG-type 2PROSITE-ProRule annotationAdd BLAST51
Nucleotide bindingi345 – 353ATPPROSITE-ProRule annotation9

GO - Molecular functioni

  • ATP binding Source: UniProtKB-KW
  • calcium-dependent protein kinase C activity Source: MGI
  • enzyme binding Source: MGI
  • histone kinase activity (H3-T6 specific) Source: MGI
  • protein kinase activity Source: MGI
  • protein kinase C activity Source: CACAO
  • protein serine/threonine kinase activity Source: MGI
  • zinc ion binding Source: InterPro

GO - Biological processi

  • angiogenesis Source: UniProtKB-KW
  • cell adhesion Source: UniProtKB-KW
  • cellular calcium ion homeostasis Source: MGI
  • cellular response to carbohydrate stimulus Source: MGI
  • chondrocyte differentiation Source: MGI
  • desmosome assembly Source: MGI
  • histone H3-T6 phosphorylation Source: MGI
  • inactivation of MAPK activity Source: MGI
  • induction of positive chemotaxis Source: MGI
  • intrinsic apoptotic signaling pathway Source: MGI
  • negative regulation of cell proliferation Source: MGI
  • negative regulation of glial cell apoptotic process Source: UniProtKB
  • negative regulation of glucose import Source: MGI
  • negative regulation of insulin receptor signaling pathway Source: MGI
  • negative regulation of protein kinase activity Source: MGI
  • negative regulation of protein phosphorylation Source: MGI
  • neutrophil chemotaxis Source: MGI
  • peptidyl-serine autophosphorylation Source: MGI
  • positive regulation of angiogenesis Source: UniProtKB
  • positive regulation of blood vessel endothelial cell migration Source: MGI
  • positive regulation of cardiac muscle hypertrophy Source: UniProtKB
  • positive regulation of cell adhesion Source: UniProtKB
  • positive regulation of cell migration Source: UniProtKB
  • positive regulation of dense core granule biogenesis Source: UniProtKB
  • positive regulation of endothelial cell migration Source: UniProtKB
  • positive regulation of endothelial cell proliferation Source: UniProtKB
  • positive regulation of ERK1 and ERK2 cascade Source: UniProtKB
  • positive regulation of inflammatory response Source: MGI
  • positive regulation of lipopolysaccharide-mediated signaling pathway Source: UniProtKB
  • positive regulation of macrophage differentiation Source: UniProtKB
  • positive regulation of mitotic cell cycle Source: UniProtKB
  • positive regulation of protein phosphorylation Source: MGI
  • protein phosphorylation Source: MGI
  • regulation of muscle contraction Source: MGI
  • regulation of peptidyl-tyrosine phosphorylation Source: MGI
  • regulation of platelet aggregation Source: UniProtKB
  • regulation of the force of heart contraction Source: MGI
  • response to interleukin-1 Source: MGI
Complete GO annotation...

Keywords - Molecular functioni

Kinase, Serine/threonine-protein kinase, Transferase

Keywords - Biological processi

Angiogenesis, Apoptosis, Cell adhesion

Keywords - Ligandi

ATP-binding, Calcium, Metal-binding, Nucleotide-binding, Zinc

Enzyme and pathway databases

BRENDAi2.7.11.13. 3474.

Names & Taxonomyi

Protein namesi
Recommended name:
Protein kinase C alpha type (EC:2.7.11.13)
Short name:
PKC-A
Short name:
PKC-alpha
Gene namesi
Name:Prkca
Synonyms:Pkca
OrganismiMus musculus (Mouse)
Taxonomic identifieri10090 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresRodentiaSciurognathiMuroideaMuridaeMurinaeMusMus
Proteomesi
  • UP000000589 Componenti: Unplaced

Organism-specific databases

MGIiMGI:97595. Prkca.

Subcellular locationi

GO - Cellular componenti

  • apical part of cell Source: MGI
  • axon Source: MGI
  • cytoplasm Source: MGI
  • cytosol Source: MGI
  • dendrite Source: MGI
  • endoplasmic reticulum Source: MGI
  • extracellular exosome Source: MGI
  • membrane Source: MGI
  • mitochondrial membrane Source: UniProtKB-SubCell
  • mitochondrion Source: MGI
  • neuronal cell body Source: MGI
  • nucleus Source: MGI
  • perinuclear region of cytoplasm Source: UniProtKB
  • photoreceptor outer segment Source: MGI
  • plasma membrane Source: MGI
Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Cytoplasm, Membrane, Mitochondrion, Nucleus

Pathology & Biotechi

Involvement in diseasei

Expression of the mutant form UV25 causes malignant transformation of cells.

Chemistry databases

ChEMBLiCHEMBL2567.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemovedBy similarity
ChainiPRO_00000556802 – 672Protein kinase C alpha typeAdd BLAST671

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei2N-acetylalanineBy similarity1
Modified residuei10PhosphoserineBy similarity1
Modified residuei226PhosphoserineBy similarity1
Modified residuei319PhosphoserineBy similarity1
Modified residuei497Phosphothreonine; by PDPK1By similarity1
Modified residuei501PhosphothreonineBy similarity1
Modified residuei628N6-acetyllysineBy similarity1
Modified residuei631Phosphothreonine; by autocatalysisSequence analysisBy similarity1
Modified residuei638Phosphothreonine; by autocatalysisBy similarity1
Modified residuei651PhosphoserineBy similarity1
Modified residuei657PhosphoserineBy similarity1
Modified residuei658Phosphotyrosine; by SYK1 Publication1

Keywords - PTMi

Acetylation, Phosphoprotein

Proteomic databases

EPDiP20444.
MaxQBiP20444.
PaxDbiP20444.
PeptideAtlasiP20444.
PRIDEiP20444.

PTM databases

iPTMnetiP20444.
PhosphoSitePlusiP20444.

Expressioni

Gene expression databases

CleanExiMM_PRKCA.

Interactioni

Subunit structurei

Interacts with ADAP1/CENTA1, CSPG4 and PRKCABP. Binds to SDPR in the presence of phosphatidylserine (By similarity). Interacts with PICK1 (via PDZ domain) (By similarity). Interacts with TRIM41 (By similarity). Recruited in a circadian manner into a nuclear complex which also includes BMAL1 and RACK1.By similarity2 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
ClockO087853EBI-6976815,EBI-79859

GO - Molecular functioni

Protein-protein interaction databases

BioGridi202194. 9 interactors.
DIPiDIP-532N.
IntActiP20444. 3 interactors.
MINTiMINT-98140.
STRINGi10090.ENSMUSP00000062392.

Chemistry databases

BindingDBiP20444.

Structurei

3D structure databases

ProteinModelPortaliP20444.
SMRiP20444.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini172 – 260C2PROSITE-ProRule annotationAdd BLAST89
Domaini339 – 597Protein kinasePROSITE-ProRule annotationAdd BLAST259
Domaini598 – 668AGC-kinase C-terminalAdd BLAST71

Sequence similaritiesi

Contains 1 AGC-kinase C-terminal domain.Curated
Contains 1 C2 domain.PROSITE-ProRule annotation
Contains 2 phorbol-ester/DAG-type zinc fingers.PROSITE-ProRule annotation
Contains 1 protein kinase domain.PROSITE-ProRule annotation

Zinc finger

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Zinc fingeri36 – 86Phorbol-ester/DAG-type 1PROSITE-ProRule annotationAdd BLAST51
Zinc fingeri101 – 151Phorbol-ester/DAG-type 2PROSITE-ProRule annotationAdd BLAST51

Keywords - Domaini

Repeat, Zinc-finger

Phylogenomic databases

eggNOGiKOG0694. Eukaryota.
ENOG410XNPH. LUCA.
HOGENOMiHOG000233022.
HOVERGENiHBG108317.
InParanoidiP20444.
KOiK02677.
PhylomeDBiP20444.

Family and domain databases

CDDicd00029. C1. 2 hits.
Gene3Di2.60.40.150. 1 hit.
InterProiIPR000961. AGC-kinase_C.
IPR000008. C2_dom.
IPR020454. DAG/PE-bd.
IPR011009. Kinase-like_dom.
IPR002219. PE/DAG-bd.
IPR017892. Pkinase_C.
IPR000719. Prot_kinase_dom.
IPR017441. Protein_kinase_ATP_BS.
IPR014375. Protein_kinase_C_a/b/g.
IPR008271. Ser/Thr_kinase_AS.
[Graphical view]
PfamiPF00130. C1_1. 2 hits.
PF00168. C2. 1 hit.
PF00069. Pkinase. 1 hit.
PF00433. Pkinase_C. 1 hit.
[Graphical view]
PIRSFiPIRSF000550. PKC_alpha. 1 hit.
PRINTSiPR00360. C2DOMAIN.
PR00008. DAGPEDOMAIN.
SMARTiSM00109. C1. 2 hits.
SM00239. C2. 1 hit.
SM00133. S_TK_X. 1 hit.
SM00220. S_TKc. 1 hit.
[Graphical view]
SUPFAMiSSF49562. SSF49562. 1 hit.
SSF56112. SSF56112. 1 hit.
PROSITEiPS51285. AGC_KINASE_CTER. 1 hit.
PS50004. C2. 1 hit.
PS00107. PROTEIN_KINASE_ATP. 1 hit.
PS50011. PROTEIN_KINASE_DOM. 1 hit.
PS00108. PROTEIN_KINASE_ST. 1 hit.
PS00479. ZF_DAG_PE_1. 2 hits.
PS50081. ZF_DAG_PE_2. 2 hits.
[Graphical view]

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

P20444-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MADVYPANDS TASQDVANRF ARKGALRQKN VHEVKDHKFI ARFFKQPTFC
60 70 80 90 100
SHCTDFIWGF GKQGFQCQVC CFVVHKRCHE FVTFSCPGAD KGPDTDDPRS
110 120 130 140 150
KHKFKIHTYG SPTFCDHCGS LLYGLIHQGM KCDTCDMNVH KQCVINDPSL
160 170 180 190 200
CGMDHTEKRG RIYLKAEVTD EKLHVTVRDA KNLIPMDPNG LSDPYVKLKL
210 220 230 240 250
IPDPKNESKQ KTKTIRSNLN PQWNESFTFK LKPSDKDRRL SVEIWDWDRT
260 270 280 290 300
TRNDFMGSLS FGVSELMKMP ASGWYKAHNQ EEGEYYNVPI PEGDEEGNME
310 320 330 340 350
LRQKFEKAKL GPVGNKVISP SEDRKQPSNN LDRVKLTDFN FLMVLGKGSF
360 370 380 390 400
GKVMLADRKG TEELYAIKIL KKDVVIQDDD VECTMVEKRV LALLDKPPFL
410 420 430 440 450
TQLHSCFQTV DRLYFVMEYV NGGDLMYHIQ QVGKFKEPQA VFYAAEISIG
460 470 480 490 500
LFFLHKRGII YRDLKLNNVM LNSEGHIKIA DFGMCKEHMM DGVTTRTFCG
510 520 530 540 550
TPDYIAPEII AYQPYGKSVD WWAYGVLLYE MLAGQPPFDG EDEDELFQSI
560 570 580 590 600
MEHNVSYPKS LSKEAVSICK GLMTKQPAKR LGCGPEGERD VREHAFFRRI
610 620 630 640 650
DWEKLENREI QPPFKPKVCG KGAENFDKFF TRGQPVLTPP DQLVIANIDQ
660 670
SDFEGFSYVN PQFVHPILQS AV
Length:672
Mass (Da):76,852
Last modified:January 23, 2007 - v3
Checksum:i394B48C952BB6D50
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti147D → V in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti147D → V in CAA36907 (PubMed:2469625).Curated1
Sequence conflicti218N → T in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti218N → T in CAA36907 (PubMed:2469625).Curated1
Sequence conflicti277 – 278AH → LL in CAA36908 (PubMed:2469625).Curated2
Sequence conflicti277 – 278AH → LL in CAA36907 (PubMed:2469625).Curated2
Sequence conflicti313V → A in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti313V → A in CAA36907 (PubMed:2469625).Curated1
Sequence conflicti467N → D in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti467N → D in CAA36907 (PubMed:2469625).Curated1
Sequence conflicti472N → D in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti472N → D in CAA36907 (PubMed:2469625).Curated1
Sequence conflicti576Q → H in CAA36908 (PubMed:2469625).Curated1
Sequence conflicti576Q → H in CAA36907 (PubMed:2469625).Curated1

Natural variant

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural varianti106I → V in mutant form UV25. 1 Publication1
Natural varianti111S → G in mutant form UV25. 1 Publication1
Natural varianti240L → Q in mutant form UV25. 1 Publication1
Natural varianti339F → L in mutant form UV25. 1 Publication1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
M25811 mRNA. Translation: AAA39934.1.
X52685 mRNA. Translation: CAA36908.1.
X52684 mRNA. Translation: CAA36907.1.
PIRiS07104. KIMSCA.
RefSeqiNP_035231.2. NM_011101.3.
UniGeneiMm.222178.

Genome annotation databases

GeneIDi18750.
KEGGimmu:18750.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
M25811 mRNA. Translation: AAA39934.1.
X52685 mRNA. Translation: CAA36908.1.
X52684 mRNA. Translation: CAA36907.1.
PIRiS07104. KIMSCA.
RefSeqiNP_035231.2. NM_011101.3.
UniGeneiMm.222178.

3D structure databases

ProteinModelPortaliP20444.
SMRiP20444.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi202194. 9 interactors.
DIPiDIP-532N.
IntActiP20444. 3 interactors.
MINTiMINT-98140.
STRINGi10090.ENSMUSP00000062392.

Chemistry databases

BindingDBiP20444.
ChEMBLiCHEMBL2567.

PTM databases

iPTMnetiP20444.
PhosphoSitePlusiP20444.

Proteomic databases

EPDiP20444.
MaxQBiP20444.
PaxDbiP20444.
PeptideAtlasiP20444.
PRIDEiP20444.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi18750.
KEGGimmu:18750.

Organism-specific databases

CTDi5578.
MGIiMGI:97595. Prkca.

Phylogenomic databases

eggNOGiKOG0694. Eukaryota.
ENOG410XNPH. LUCA.
HOGENOMiHOG000233022.
HOVERGENiHBG108317.
InParanoidiP20444.
KOiK02677.
PhylomeDBiP20444.

Enzyme and pathway databases

BRENDAi2.7.11.13. 3474.

Miscellaneous databases

ChiTaRSiPrkca. mouse.
PROiP20444.
SOURCEiSearch...

Gene expression databases

CleanExiMM_PRKCA.

Family and domain databases

CDDicd00029. C1. 2 hits.
Gene3Di2.60.40.150. 1 hit.
InterProiIPR000961. AGC-kinase_C.
IPR000008. C2_dom.
IPR020454. DAG/PE-bd.
IPR011009. Kinase-like_dom.
IPR002219. PE/DAG-bd.
IPR017892. Pkinase_C.
IPR000719. Prot_kinase_dom.
IPR017441. Protein_kinase_ATP_BS.
IPR014375. Protein_kinase_C_a/b/g.
IPR008271. Ser/Thr_kinase_AS.
[Graphical view]
PfamiPF00130. C1_1. 2 hits.
PF00168. C2. 1 hit.
PF00069. Pkinase. 1 hit.
PF00433. Pkinase_C. 1 hit.
[Graphical view]
PIRSFiPIRSF000550. PKC_alpha. 1 hit.
PRINTSiPR00360. C2DOMAIN.
PR00008. DAGPEDOMAIN.
SMARTiSM00109. C1. 2 hits.
SM00239. C2. 1 hit.
SM00133. S_TK_X. 1 hit.
SM00220. S_TKc. 1 hit.
[Graphical view]
SUPFAMiSSF49562. SSF49562. 1 hit.
SSF56112. SSF56112. 1 hit.
PROSITEiPS51285. AGC_KINASE_CTER. 1 hit.
PS50004. C2. 1 hit.
PS00107. PROTEIN_KINASE_ATP. 1 hit.
PS50011. PROTEIN_KINASE_DOM. 1 hit.
PS00108. PROTEIN_KINASE_ST. 1 hit.
PS00479. ZF_DAG_PE_1. 2 hits.
PS50081. ZF_DAG_PE_2. 2 hits.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiKPCA_MOUSE
AccessioniPrimary (citable) accession number: P20444
Entry historyi
Integrated into UniProtKB/Swiss-Prot: February 1, 1991
Last sequence update: January 23, 2007
Last modified: November 30, 2016
This is version 178 of the entry and version 3 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. MGD cross-references
    Mouse Genome Database (MGD) cross-references in UniProtKB/Swiss-Prot
  2. Human and mouse protein kinases
    Human and mouse protein kinases: classification and index
  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.