KEGG ENZYME: 3.4.24.86

ENZYME: 3.4.24.86

Entry

EC 3.4.24.86                Enzyme

Name

ADAM 17 endopeptidase;
tumor necrosis factor alpha-converting enzyme;
TACE

Class

Hydrolases;
Acting on peptide bonds (peptidases);
Metalloendopeptidases

Reaction(IUBMB)

Narrow endopeptidase specificity. Cleaves Pro-Leu-Ala-Gln-Ala!Val-Arg-Ser-Ser-Ser in the membrane-bound, 26-kDa form of tumour necrosis factor alpha (TNFalpha). Similarly cleaves other membrane-anchored, cell-surface proteins to "shed" the extracellular domains

Comment

In peptidase family M12. In vivo, the cleavage of tumour necrosis factor alpha precursor releases the soluble, 17-kDa TNFalpha, which induces inflammation.

History

EC 3.4.24.86 created 2003

Orthology

K06059

disintegrin and metalloproteinase domain-containing protein 17

Genes

HSA:	6868(ADAM17)

PTR:	459018(ADAM17)

PPS:	100988650(ADAM17)

GGO:	101152705(ADAM17)

PON:	100439426(ADAM17)

NLE:	100605134(ADAM17)

HMH:	116480211(ADAM17)

MCC:	694429(ADAM17)

MCF:	102116784(ADAM17)

MTHB:

126933776

MNI:	105486511(ADAM17)

CSAB:

103220846(ADAM17)

CATY:

105587543(ADAM17)

PANU:

100126726(ADAM17)

TGE:	112604761(ADAM17)

MLEU:

105528533(ADAM17)

RRO:	104675213(ADAM17)

RBB:	108516165(ADAM17)

TFN:	117062750(ADAM17)

PTEH:

111531765(ADAM17)

CANG:

105525335(ADAM17)

CJC:	100406520(ADAM17)

SBQ:	101049053(ADAM17)

CIMI:

108301849(ADAM17)

CSYR:

103273750(ADAM17)

MMUR:

105882940(ADAM17)

LCAT:

123636584(ADAM17)

PCOQ:

105806730(ADAM17)

OGA:	100947870(ADAM17)

MMU:	11491(Adam17)

MCAL:

110306467(Adam17)

MPAH:

110324376(Adam17)

RNO:	57027(Adam17)

MCOC:

116080989(Adam17)

ANU:	117716809(Adam17)

MUN:	110564190(Adam17)

CGE:	100684971(Adam17)

MAUA:

101828493(Adam17)

PROB:

127215298 127237593(Adam17)

PLEU:

114698857(Adam17)

MORG:

121432399(Adam17) 121438902

MFOT:

126501305

AAMP:

119807826(Adam17)

NGI:	103747629(Adam17)

HGL:	101720924(Adam17)

CPOC:

100732916(Adam17)

CCAN:

109695934(Adam17)

DORD:

105983695(Adam17)

DSP:	122108773(Adam17)

PLOP:

125356745(Adam17)

NCAR:

124962735

MMMA:

107137509(Adam17)

OCU:

100101613

OPI:	101532279(ADAM17)

TUP:	102496316(ADAM17)

GVR:	103610686(ADAM17)

CFA:	475662(ADAM17)

CLUD:

112664856(ADAM17)

VVP:	112927728(ADAM17)

VLG:	121491142(ADAM17)

NPO:	129510838(ADAM17)

AML:	100482770(ADAM17)

UMR:	103675912(ADAM17)

UAH:	113269710(ADAM17)

UAR:	123778537(ADAM17)

ELK:

111154187

LLV:

125108380

MPUF:

101678822(ADAM17)

MNP:	132021122(ADAM17)

MLK:	131807398(ADAM17)

NVS:	122915325(ADAM17)

ORO:	101378266(ADAM17)

EJU:	114205773(ADAM17)

ZCA:	113937386(ADAM17)

MLX:	118007302 118007360

NSU:	110587392(ADAM17)

LWW:	102738586(ADAM17)

FCA:	101089004(ADAM17)

PYU:	121044072(ADAM17)

PCOO:

112864061(ADAM17)

PBG:	122497481(ADAM17)

PVIV:

125158339(ADAM17)

LRUF:

124503705

PTG:	102948618(ADAM17)

PPAD:

109268814(ADAM17)

PUC:

125937696

AJU:

106982950

HHV:	120231128(ADAM17)

BTA:	517541(ADAM17)

BOM:	102279111(ADAM17)

BIU:	109566404(ADAM17)

BBUB:

102393245(ADAM17)

BBIS:

104997349(ADAM17)

CHX:	102188327(ADAM17)

OAS:	101116815(ADAM17)

BTAX:

128055238(ADAM17)

ODA:	120851888(ADAM17)

CCAD:

122442085(ADAM17)

MBEZ:

129539087(ADAM17)

SSC:	397343(ADAM17)

CFR:	102508816(ADAM17)

CBAI:

105076036(ADAM17)

CDK:	105091236(ADAM17)

VPC:	102542735(ADAM17)

BACU:

103004501(ADAM17)

BMUS:

118905722(ADAM17)

LVE:	103086820(ADAM17)

OOR:	101272366(ADAM17)

DLE:	111164496(ADAM17)

PCAD:

102978565(ADAM17)

PSIU:

116763969(ADAM17)

NASI:

112394765(ADAM17)

ECB:	100072496(ADAM17)

EPZ:	103543937 103560849(ADAM17)

EAI:	106847480(ADAM17)

MYB:	102256292(ADAM17)

MYD:	102767398(ADAM17)

MMYO:

118669297(ADAM17)

MLF:	102425078(ADAM17)

PKL:	118715935(ADAM17)

EFUS:

103305599(ADAM17)

MNA:	107526643(ADAM17)

DRO:	112297707(ADAM17)

SHON:

118988749(ADAM17)

AJM:	119053993(ADAM17)

PDIC:

114499294(ADAM17)

PHAS:

123822573(ADAM17)

MMF:	118630463(ADAM17)

PPAM:

129067690(ADAM17)

HAI:	109386655(ADAM17)

RFQ:	117032918(ADAM17)

PALE:

102894565(ADAM17)

PGIG:

120622059(ADAM17)

PVP:	105295437(ADAM17)

RAY:	107498263(ADAM17)

MJV:	108398652(ADAM17) 108406598

TOD:	119259567(ADAM17)

SARA:

101541255(ADAM17)

LAV:	100663807(ADAM17)

TMU:

101350544

ETF:	101641143(ADAM17)

DNM:	101418734(ADAM17)

MDO:	100032069(ADAM17)

GAS:	123237029(ADAM17)

SHR:	100926795(ADAM17)

AFZ:

127548615

PCW:	110212614(ADAM17)

OAA:	100086345(ADAM17)

GGA:	421931(ADAM17)

PCOC:

116240757(ADAM17)

MGP:	100549409(ADAM17)

CJO:	107312200(ADAM17)

TPAI:

128088191(ADAM17)

LMUT:

125689571(ADAM17)

NMEL:

110395713(ADAM17)

APLA:

101794295(ADAM17)

ACYG:

106030708(ADAM17)

CATA:

118246149(ADAM17)

AFUL:

116487500(ADAM17)

TGU:	100225922(ADAM17)

LSR:	110467958(ADAM17)

SCAN:

103820444(ADAM17)

PMOA:

120505304(ADAM17)

OTC:	121344379(ADAM17)

PRUF:

121359136(ADAM17)

GFR:	102034165(ADAM17)

FAB:	101814343(ADAM17)

OMA:	130251684(ADAM17)

PHI:	102106429(ADAM17)

PMAJ:

107201529(ADAM17)

CCAE:

111925944(ADAM17)

CCW:	104685448(ADAM17)

CBRC:

103622851(ADAM17)

ETL:	114058979(ADAM17)

ZAB:	102062655(ADAM17)

ACHL:

103811209(ADAM17)

SVG:	106865122(ADAM17)

MMEA:

130576652(ADAM17)

HRT:	120749949(ADAM17)

FPG:	101924106(ADAM17)

FCH:	102055911(ADAM17)

CLV:	102098173(ADAM17)

EGZ:	104127159(ADAM17)

NNI:	104013024(ADAM17)

PCRI:

104031903(ADAM17)

PLET:

104622291(ADAM17)

PCAO:

104053058(ADAM17)

ACUN:

113478354(ADAM17)

TALA:

104357741(ADAM17)

PADL:

103924054(ADAM17)

AFOR:

103895885(ADAM17)

ACHC:

115350914(ADAM17)

HLE:	104831248(ADAM17)

AGEN:

126046408

GCL:

127014468

CCRI:

104162249(ADAM17)

CSTI:

104550091(ADAM17)

CMAC:

104484666(ADAM17)

MUI:	104539665(ADAM17)

BREG:

104638126(ADAM17)

FGA:	104075420(ADAM17)

GSTE:

104253426(ADAM17)

LDI:	104350533(ADAM17)

MNB:	103776199(ADAM17)

OHA:	104336253(ADAM17)

NNT:	104399631(ADAM17)

SHAB:

115609394(ADAM17)

DPUB:

104308101(ADAM17)

PGUU:

104463942(ADAM17)

ACAR:

104522582(ADAM17)

CPEA:

104390068(ADAM17)

CVF:	104293745(ADAM17)

RTD:	128906738(ADAM17)

CUCA:

104066457(ADAM17)

TEO:	104371691(ADAM17)

BRHI:

104492889(ADAM17)

AAM:	106494759(ADAM17)

AROW:

112976492(ADAM17)

NPD:	112945452(ADAM17)

TGT:	104576511(ADAM17)

DNE:	112981540(ADAM17)

SCAM:

104147606(ADAM17)

ASN:	102373202(ADAM17)

AMJ:	102560812(ADAM17)

CPOO:

109312094(ADAM17)

GGN:	109300145(ADAM17)

PSS:	102454376(ADAM17)

CMY:	102933390(ADAM17)

CCAY:

125634554(ADAM17)

DCC:	119853372(ADAM17)

CPIC:

101938160(ADAM17)

TST:	117875291(ADAM17)

CABI:

116823114(ADAM17)

MRV:	120401271(ADAM17)

ACS:	100563907(adam17)

ASAO:

132782703(ADAM17)

PVT:	110080585(ADAM17)

SUND:

121927898(ADAM17)

PBI:	103060091(ADAM17)

PMUR:

107295813(ADAM17)

CTIG:

120302866(ADAM17)

PGUT:

117674213(ADAM17)

APRI:

131195933(ADAM17)

PTEX:

113432968(ADAM17)

NSS:	113416457(ADAM17)

VKO:	123017146(ADAM17)

PMUA:

114593781(ADAM17)

PRAF:

128410153(ADAM17)

ZVI:	118082396(ADAM17)

HCG:	128340529(ADAM17)

GJA:	107112820(ADAM17)

STOW:

125433705(ADAM17)

EMC:	129333377(ADAM17)

XLA:	108718238(adam17.S) 733430(adam17.L)

XTR:	100492947(adam17)

NPR:	108789869(ADAM17)

RTEM:

120936358(ADAM17)

BBUF:

120997413(ADAM17)

BGAR:

122933687 122934891

MUO:	115467158(ADAM17)

GSH:	117356874(ADAM17)

DRE:	324142(adam17a) 560657(adam17b)

SRX:	107707689 107721298(adam17) 107752755 107756583

SANH:

107655315 107668236 107679802(adam17) 107693239

SGH:	107549102 107553270 107563905 107601850

CCAR:

109102614 109108207

CAUA:

113060579 113062863 113063206 113078559 113117279

CGIB:

127933475 127938250 127976588 127983609

PTET:

122324794(adam17b) 122361857(adam17a)

LROH:

127179302(adam17a) 127182844(adam17b)

OMC:	131523616(adam17a) 131527724(adam17b)

PPRM:

120476738(adam17a) 120493978(adam17b)

RKG:	130075457(adam17b) 130080283(adam17a)

MAMB:

125269329(adam17a) 125277828(adam17b)

CIDE:

127498026 127498187 127502958

MASI:

127410155 127411257 127416487 127455512

TROS:

130560624(adam17a) 130565599(adam17b)

TDW:	130434396(adam17b) 130437270(adam17a)

MANU:

129417404(adam17a) 129429321(adam17b)

IPU:	108257789(adam17b) 108270063(adam17a)

IFU:	128601062(adam17b) 128612996(adam17a)

PHYP:

113531802 113538559(adam17)

SMEO:

124377472(adam17b) 124390219(adam17a)

TFD:	113655629(adam17b) 113659686(adam17a)

TVC:	132843230(adam17b) 132852675(adam17a)

AMEX:

103041369 103041996

CMAO:

118815633(adam17b) 118823462(adam17a)

EEE:	113570511 113579136(adam17)

CHAR:

105897061(adam17b) 105897267(adam17a)

TRU:	101063716(adam17) 101075639

TFS:	130516153(adam17b) 130539694(adam17a)

TNG:	GSTEN00003450G001 GSTEN00032183G001

LCO:	104922135 104938532

NCC:	104953609(adam17)

TBEN:

117473782(adam17a)

CGOB:

115027586(adam17)

PGEO:

117467499

GACU:

117549910

EMAC:

134877193(adam17b) 134881429(adam17a)

ELY:	117266979(adam17a) 117270804(adam17b)

EFO:	125896904(adam17b) 125900530(adam17a)

PLEP:

121953389(adam17a) 121955712

SLUC:

116035705(adam17a) 116061359

ECRA:

117936317(adam17a)

ESP:	116670032(adam17)

PFLV:

114546481(adam17)

GAT:	120815238 120833295(adam17a)

PPUG:

119195236 119227477(adam17a)

AFB:	129103252(adam17a) 129107002(adam17b)

CLUM:

117751347(adam17a)

PSWI:

130202053(adam17a)

MSAM:

119909392(adam17b) 119910413(adam17a)

SCHU:

122861718(adam17a) 122862643(adam17b)

CUD:	121521362(adam17b) 121526184(adam17a)

ALAT:

119004926(adam17a) 119012752(adam17b)

MZE:	101474055 101477206

ONL:	100692440 100700935

OAU:	116312411(adam17b) 116334721(adam17a)

OLA:	101165277 101171872

OML:	112149788(adam17a) 112157702(adam17b)

CSAI:

133461983(adam17a) 133464880(adam17b)

XMA:	102222153 102227287(adam17)

XCO:	114134256 114158418(adam17)

XHE:	116709412 116734229(adam17)

PRET:

103457157(adam17) 103458871

PFOR:

103144243 103146799(adam17)

PLAI:

106954181 106958488(adam17)

PMEI:

106925343(adam17) 106926881

GAF:	122825649(adam17b) 122846679(adam17a)

PPRL:

129354515(adam17b) 129374730

CVG:	107087577 107089571(adam17)

CTUL:

119784254(adam17a) 119789424(adam17b)

GMU:	124855404 124882393(adam17b)

NFU:	107377926 107392286(adam17)

KMR:	108236986(adam17a) 108249691(adam17b)

ALIM:

106521553 106530770(adam17)

NWH:	119418690(adam17b) 119427330(adam17a)

AOCE:

111565930 111587227

MCEP:

124998878(adam17b) 125023604(adam17a)

CSEM:

103377555(adam17) 103381366

POV:	109628009 109647613 109647706

SSEN:

122782844(adam17a) 122784344(adam17b)

HHIP:

117755872(adam17a) 117758776(adam17b)

HSP:	118104017(adam17b) 118116343(adam17a)

SMAU:

118286480(adam17a) 118289970(adam17b)

LCF:	108888136(adam17a) 108891569(adam17b)

SDU:	111225559 111236091

SLAL:

111644771(adam17) 111672592

XGL:	120788898(adam17b) 120795416(adam17a)

HCQ:	109526133(adam17) 109531720

SSCV:

125981403 125990485

SBIA:

133496315(adam17b) 133513442(adam17a)

PEE:	133412516(adam17a) 133417292(adam17b)

PTAO:

133468402(adam17b) 133488146(adam17a)

BPEC:

110155414(adam17) 110164254

MALB:

109955016 109974460

BSPL:

114847944(adam17a) 114849978(adam17b)

SJO:	128375934(adam17a) 128377021(adam17b)

SASA:

106566892 106607660 106610723

STRU:

115162529 115172824 115195042

OTW:	112217454(adam17b) 112247281 112256502(adam17a)

OMY:	110498110 110505320(adam17a) 110522060(adam17b)

OGO:	123994869(adam17b) 124001138 124046303(adam17a)

ONE:	115138326 115139643 115146388

OKI:	109866323 109894643 109903890

OKE:	118362310 118368488 118386674(adam17b)

SALP:

111963100 111968888 111972678

SNH:	120019620(adam17b) 120023088(adam17a) 120060189

CCLU:

121539398 121545088 121566828(adam17b)

ELS:	105016077 105017805 114829444

SFM:	108921884(adam17)

PKI:

111842019

AANG:

118223873 118230860(adam17b)

LOC:	102682214(adam17)

PSPA:

121315402 121317536(adam17b)

ARUT:

117402183(adam17a) 117411384(adam17b)

PSEX:

120526040(adam17b)

LCM:	102367618(ADAM17)

CMK:	103187122(adam17b)

CPLA:

122541365(adam17b)

HOC:	132834418(adam17b)

LERI:

129697077(adam17b)

PMRN:

116942526 116951388(ADAM17)

LRJ:	133340851 133340852 133349091

BFO:

118404014

BBEL:

109473119

CIN:

100175230

SCLV:

120332865

SPU:

585715

LPIC:

129264781

APLC:

110985040

AJC:

117103049

SKO:

102803736

DME:	Dmel_CG7908(Tace)

DER:

6554190

DSE:

6612793

DSI:	Dsimw501_GD21492(Dsim_GD21492)

DYA:	Dyak_GE10847

DAN:

6501584

DSR:

110186406

DPO:

6896714

DPE:

6594801

DMN:

108155302

DWI:

6650344

DGR:

6567576

DMO:	Dmoj_GI10801

DAZ:

108609115

DNV:

108659297

DHE:

111596420

DVI:

6635224

CCAT:

101448581

BOD:

106618981

BDR:

105225774

RZE:

108361250

AOQ:

129239624

TDA:	119677694 119683338

MDE:	101891592 131805884

SCAC:

106081862

LCQ:

111686124

LSQ:

119601926

GFS:

119635009

ECOE:

129939823

CLON:

129607063

HIS:

119650619

AGA:

1273579

ACOZ:

120949087

AARA:

120894455

AMER:

121590638

ASTE:

118502845

AFUN:

125763313

AMOU:

128301613

AALI:

118457949

AAG:

5563722

AALB:

109424331

CQU:	CpipJ_CPIJ005931

CPII:

120421188

CNS:

116346870

BCOO:

119069712

AME:

551599

ACER:

108000097

ALAB:

122717424

ADR:

102674053

AFLR:

100868051

BIM:

100745543

BBIF:

117212151

BVK:

117240411

BVAN:

117162798

BTER:

100645870

BAFF:

126914335

BPYO:

122566715

BPAS:

132909761

FVI:

122527570

CCAL:

108623713

OBB:

114877479

OLG:

117607800

MGEN:

117227229

NMEA:

116432844

CGIG:

122396464

SOC:

105197464

MPHA:

105839042

AEC:

105143101

ACEP:

105623272

PBAR:

105427116

VEM:

105561144

HST:

105184135

DQU:

106750237

CFO:

105258924

FEX:

115241593

LHU:

105669279

PGC:

109861730

OBO:

105282848

PCF:

106793988

PFUC:

122521241

VPS:

122637869

VCRB:

124422154

VVE:

124956652

NVI:

100119121

CSOL:

105364600

TPRE:

106654176

LHT:

122502437

LBD:

127289378

MDL:

103578657

CGLO:

123270939

FAS:

105266951

DAM:

107041094

AGIF:

122855408

CINS:

118073841

VCAN:

122406705

CCIN:

107265431

DSM:

124408540

NPT:

124211666

NFB:

124187719

NLO:

107226342

NVG:

124298125

AROA:

105690398

TCA:

663540

DPA:

109537991

SOY:

115875020

AGRG:

126748933

ATD:

109602707

CSET:

123315085 123318618

AGB:

108914225

LDC:

111506628

NVL:

108563900

APLN:

108738958 112904002

PPYR:

116161187

OTU:

111419993

BMOR:

101742406

BMAN:

114240363

MSEX:

115440097

DPL:	KGM_202512

BANY:

112051369

MJU:

123874356

NIQ:

126773170

VCD:

124534830

MCIX:

123659170

PMAC:

106713573

PPOT:

106104922

PXU:

106122629

PRAP:

111003508

PBX:

123706897

PNAP:

125050368

CCRC:

123698644

LSIN:

126967438

AAGE:

121734141

HAW:

110384278

HZE:

124637015

TNL:

113503404

SLIU:

111354966

OFU:

114352070

PXY:

105386060

PGW:

126370922

CFEL:

113372468

CCRN:

123305992

API:

100158671

DNX:

107167450

AGS:

114130986

RMD:

113559354

ACOO:

126839611 126843026

DVT:

126902802

BTAB:

109032996

DCI:

103515131

CLEC:

106673239

HHAL:

106685230

NLU:

111053184

HVI:

124361784

MQU:

128988521

PHU:	Phum_PHUM024730

FOC:

113217343

TPAL:

117654419

ZNE:

110836194

CSEC:

111874896 111875197

SGRE:

126267245

BROR:

134533754

IEL:

124154096

FCD:

110845600

DPX:	DAPPUDRAFT_314368

DMK:	116925958 123470055

DPZ:

124340918

PVM:	113801174 113801176

PJA:	122247615 122264652

PCHN:

125046731 125046761

PMOO:

119591392 119591553

HAME:

121869162

PCLA:

123764791

CQD:

128696329

PTRU:

123504923

ESN:

126996497

MNZ:	135204219 135204236 135204237

HAZT:

108674819

EAF:

111713207

LSM:	121117760 121118487

TCF:

131877982

PPOI:

119100663 119100666 119100667

ISC:

120835932

DSV:

119460684

RSAN:

119396531

RMP:

119174711

VDE:	111247675 111248881 111249277 111249387 111250104 111250143

VJA:	111259527 111264350 111264356 111265748 111269090 111269228

DFR:	124498186 124498350

CSCU:

111618821

PTEP:

107455115

ABRU:

129958549

UDV:

129230976

SDM:

118180981

PMEO:

129589025

CEL:	CELE_ZK154.7(adm-4)

CBR:	CBG_16796(Cbr-adm-4)

CRQ:	GCK72_024847

NAI:	NECAME_00683

BMY:	BM_BM7430(Bma-adm-4)

LOA:	LOAG_03310

TSP:

Tsp_02601

LGI:	LOTGIDRAFT_140416 LOTGIDRAFT_218462

PVUL:

126831602 126832499

PCAN:

112559081 112559083 112559089 112559955 112560031 112560314 112561901 112570179 112577068

BGT:	106052851 106054305 106057281 106057282 106057867 106068788

GAE:	121387517 121387804

HRF:	124125268 124149260

HRJ:	124265245 124272395

CRG:	105322445 105330896 105338334 105338464 105348437

CVN:	111123307 111125232 111126918 111127133 111127575 111127576 111133224

CANU:

128156361 128179872 128180124 128192123 128192532

OED:	125657630 125668371 125680934 125681006 125681301

MYI:	110445809 110449224 110453479 110456857 110458138

PMAX:

117317391 117317665 117317752 117339393

MMER:

123538796 123538949

RPHI:

132721796 132721819

DPOL:

127831834 127848415

OBI:

106881514

OSN:

115220007

LAK:

106153651

SMM:	Smp_175340.1

SHX:	MS3_00006789(ADAM17)

OVI:	T265_01230

EGL:

EGR_00581

NVE:

5511423

EPA:

110250562

ATEN:

116292316

ADF:

107358831

AMIL:

114948654

PDAM:

113681067

SPIS:

111328065

DGT:

114528597

XEN:

124447472

HMG:

100210793

HSY:	130614752 130614753

TAD:	TRIADDRAFT_58971

AQU:	105311941 105312617 105315908

EIN:	Eint_060290

EHE:	EHEL_060310

ERO:	EROM_060290

MBR:	MONBRDRAFT_22131 MONBRDRAFT_22277 MONBRDRAFT_24567

SRE:	PTSG_06305 PTSG_07102 PTSG_07278

» show all

Reference

1 [PMID:11733179]

Authors

Black RA.

Title

Tumor necrosis factor-alpha converting enzyme.

Journal

Int J Biochem Cell Biol 34:1-5 (2002)
DOI:10.1016/S1357-2725(01)00097-8

Other DBs

ExplorEnz - The Enzyme Database:

3.4.24.86

IUBMB Enzyme Nomenclature:

3.4.24.86

ExPASy - ENZYME nomenclature database:

3.4.24.86

BRENDA, the Enzyme Database:

3.4.24.86

CAS:	151769-16-3

DBGET integrated database retrieval system