'''Faktor V''' ('''faktor pet''') jest [[protein]] sistema [[koagulacija|koagulacije]], koji je kod [[ljudi]] [[kodon|kodiran]] [[gen]]om  '''FV''' sa [[hromosom 1|hromosoma 1, regija1q24]]. Rijetko se naziva '''proakcelerin''' ili '''labilni faktor'''. Za razliku od većine drugih faktora koagulacije, nije [[enzim]]ski aktivan, ali funkcioniše kao [[Kofaktor (biohemija)|kofaktor]]. Nedostatak dovodi do predispozicije za [[krvarenje|hemoragiju]], dok neke mutacije (najčešće [[faktor V Leiden]]) predisponiraju za [[tromboza|trombozu]].
 
[[Genom]]ski je srodan familiji [[multibakar-oksidaza]] i homologan je koagulacijskom [[faktor VIII|faktoru VIII]]. Gen se prostire na 70 kb, sastoji se od 25 [[egzon]]a, a rezultirajući protein ima relativnu molekulsku masu od približno 330 kDa.
 
==Aminokiselinska sekvenca==
Dužina [[polipeptid]]nog lanca je  2&nbsp;224  [[aminokiseline]], a [[molekularna masa|molekulska težina]] 251.703 [[dalton (jedinica)|Da]].
{{legenda aminokiselina}} 
<table style="font-family:monospace;">
<tr style="text-align:right;"><th>10</th><th></th><th>20</th><th></th><th>30</th><th></th><th>40</th><th></th><th>50</th></tr>
<tr style="background-color: #eee;"><td>MFPGCPRLWV</td><td style="background-color: #f9f9f9;"></td><td>LVVLGTSWVG</td><td style="background-color: #f9f9f9;"></td><td>WGSQGTEAAQ</td><td style="background-color: #f9f9f9;"></td><td>LRQFYVAAQG</td><td style="background-color: #f9f9f9;"></td><td>ISWSYRPEPT</td></tr>
<tr style="background-color: #eee;"><td>NSSLNLSVTS</td><td style="background-color: #f9f9f9;"></td><td>FKKIVYREYE</td><td style="background-color: #f9f9f9;"></td><td>PYFKKEKPQS</td><td style="background-color: #f9f9f9;"></td><td>TISGLLGPTL</td><td style="background-color: #f9f9f9;"></td><td>YAEVGDIIKV</td></tr>
<tr style="background-color: #eee;"><td>HFKNKADKPL</td><td style="background-color: #f9f9f9;"></td><td>SIHPQGIRYS</td><td style="background-color: #f9f9f9;"></td><td>KLSEGASYLD</td><td style="background-color: #f9f9f9;"></td><td>HTFPAEKMDD</td><td style="background-color: #f9f9f9;"></td><td>AVAPGREYTY</td></tr>
<tr style="background-color: #eee;"><td>EWSISEDSGP</td><td style="background-color: #f9f9f9;"></td><td>THDDPPCLTH</td><td style="background-color: #f9f9f9;"></td><td>IYYSHENLIE</td><td style="background-color: #f9f9f9;"></td><td>DFNSGLIGPL</td><td style="background-color: #f9f9f9;"></td><td>LICKKGTLTE</td></tr>
<tr style="background-color: #eee;"><td>GGTQKTFDKQ</td><td style="background-color: #f9f9f9;"></td><td>IVLLFAVFDE</td><td style="background-color: #f9f9f9;"></td><td>SKSWSQSSSL</td><td style="background-color: #f9f9f9;"></td><td>MYTVNGYVNG</td><td style="background-color: #f9f9f9;"></td><td>TMPDITVCAH</td></tr>
<tr style="background-color: #eee;"><td>DHISWHLLGM</td><td style="background-color: #f9f9f9;"></td><td>SSGPELFSIH</td><td style="background-color: #f9f9f9;"></td><td>FNGQVLEQNH</td><td style="background-color: #f9f9f9;"></td><td>HKVSAITLVS</td><td style="background-color: #f9f9f9;"></td><td>ATSTTANMTV</td></tr>
<tr style="background-color: #eee;"><td>GPEGKWIISS</td><td style="background-color: #f9f9f9;"></td><td>LTPKHLQAGM</td><td style="background-color: #f9f9f9;"></td><td>QAYIDIKNCP</td><td style="background-color: #f9f9f9;"></td><td>KKTRNLKKIT</td><td style="background-color: #f9f9f9;"></td><td>REQRRHMKRW</td></tr>
<tr style="background-color: #eee;"><td>EYFIAAEEVI</td><td style="background-color: #f9f9f9;"></td><td>WDYAPVIPAN</td><td style="background-color: #f9f9f9;"></td><td>MDKKYRSQHL</td><td style="background-color: #f9f9f9;"></td><td>DNFSNQIGKH</td><td style="background-color: #f9f9f9;"></td><td>YKKVMYTQYE</td></tr>
<tr style="background-color: #eee;"><td>DESFTKHTVN</td><td style="background-color: #f9f9f9;"></td><td>PNMKEDGILG</td><td style="background-color: #f9f9f9;"></td><td>PIIRAQVRDT</td><td style="background-color: #f9f9f9;"></td><td>LKIVFKNMAS</td><td style="background-color: #f9f9f9;"></td><td>RPYSIYPHGV</td></tr>
<tr style="background-color: #eee;"><td>TFSPYEDEVN</td><td style="background-color: #f9f9f9;"></td><td>SSFTSGRNNT</td><td style="background-color: #f9f9f9;"></td><td>MIRAVQPGET</td><td style="background-color: #f9f9f9;"></td><td>YTYKWNILEF</td><td style="background-color: #f9f9f9;"></td><td>DEPTENDAQC</td></tr>
<tr style="background-color: #eee;"><td>LTRPYYSDVD</td><td style="background-color: #f9f9f9;"></td><td>IMRDIASGLI</td><td style="background-color: #f9f9f9;"></td><td>GLLLICKSRS</td><td style="background-color: #f9f9f9;"></td><td>LDRRGIQRAA</td><td style="background-color: #f9f9f9;"></td><td>DIEQQAVFAV</td></tr>
<tr style="background-color: #eee;"><td>FDENKSWYLE</td><td style="background-color: #f9f9f9;"></td><td>DNINKFCENP</td><td style="background-color: #f9f9f9;"></td><td>DEVKRDDPKF</td><td style="background-color: #f9f9f9;"></td><td>YESNIMSTIN</td><td style="background-color: #f9f9f9;"></td><td>GYVPESITTL</td></tr>
<tr style="background-color: #eee;"><td>GFCFDDTVQW</td><td style="background-color: #f9f9f9;"></td><td>HFCSVGTQNE</td><td style="background-color: #f9f9f9;"></td><td>ILTIHFTGHS</td><td style="background-color: #f9f9f9;"></td><td>FIYGKRHEDT</td><td style="background-color: #f9f9f9;"></td><td>LTLFPMRGES</td></tr>
<tr style="background-color: #eee;"><td>VTVTMDNVGT</td><td style="background-color: #f9f9f9;"></td><td>WMLTSMNSSP</td><td style="background-color: #f9f9f9;"></td><td>RSKKLRLKFR</td><td style="background-color: #f9f9f9;"></td><td>DVKCIPDDDE</td><td style="background-color: #f9f9f9;"></td><td>DSYEIFEPPE</td></tr>
<tr style="background-color: #eee;"><td>STVMATRKMH</td><td style="background-color: #f9f9f9;"></td><td>DRLEPEDEES</td><td style="background-color: #f9f9f9;"></td><td>DADYDYQNRL</td><td style="background-color: #f9f9f9;"></td><td>AAALGIRSFR</td><td style="background-color: #f9f9f9;"></td><td>NSSLNQEEEE</td></tr>
<tr style="background-color: #eee;"><td>FNLTALALEN</td><td style="background-color: #f9f9f9;"></td><td>GTEFVSSNTD</td><td style="background-color: #f9f9f9;"></td><td>IIVGSNYSSP</td><td style="background-color: #f9f9f9;"></td><td>SNISKFTVNN</td><td style="background-color: #f9f9f9;"></td><td>LAEPQKAPSH</td></tr>
<tr style="background-color: #eee;"><td>QQATTAGSPL</td><td style="background-color: #f9f9f9;"></td><td>RHLIGKNSVL</td><td style="background-color: #f9f9f9;"></td><td>NSSTAEHSSP</td><td style="background-color: #f9f9f9;"></td><td>YSEDPIEDPL</td><td style="background-color: #f9f9f9;"></td><td>QPDVTGIRLL</td></tr>
<tr style="background-color: #eee;"><td>SLGAGEFKSQ</td><td style="background-color: #f9f9f9;"></td><td>EHAKHKGPKV</td><td style="background-color: #f9f9f9;"></td><td>ERDQAAKHRF</td><td style="background-color: #f9f9f9;"></td><td>SWMKLLAHKV</td><td style="background-color: #f9f9f9;"></td><td>GRHLSQDTGS</td></tr>
<tr style="background-color: #eee;"><td>PSGMRPWEDL</td><td style="background-color: #f9f9f9;"></td><td>PSQDTGSPSR</td><td style="background-color: #f9f9f9;"></td><td>MRPWKDPPSD</td><td style="background-color: #f9f9f9;"></td><td>LLLLKQSNSS</td><td style="background-color: #f9f9f9;"></td><td>KILVGRWHLA</td></tr>
<tr style="background-color: #eee;"><td>SEKGSYEIIQ</td><td style="background-color: #f9f9f9;"></td><td>DTDEDTAVNN</td><td style="background-color: #f9f9f9;"></td><td>WLISPQNASR</td><td style="background-color: #f9f9f9;"></td><td>AWGESTPLAN</td><td style="background-color: #f9f9f9;"></td><td>KPGKQSGHPK</td></tr>
<tr style="background-color: #eee;"><td>FPRVRHKSLQ</td><td style="background-color: #f9f9f9;"></td><td>VRQDGGKSRL</td><td style="background-color: #f9f9f9;"></td><td>KKSQFLIKTR</td><td style="background-color: #f9f9f9;"></td><td>KKKKEKHTHH</td><td style="background-color: #f9f9f9;"></td><td>APLSPRTFHP</td></tr>
<tr style="background-color: #eee;"><td>LRSEAYNTFS</td><td style="background-color: #f9f9f9;"></td><td>ERRLKHSLVL</td><td style="background-color: #f9f9f9;"></td><td>HKSNETSLPT</td><td style="background-color: #f9f9f9;"></td><td>DLNQTLPSMD</td><td style="background-color: #f9f9f9;"></td><td>FGWIASLPDH</td></tr>
<tr style="background-color: #eee;"><td>NQNSSNDTGQ</td><td style="background-color: #f9f9f9;"></td><td>ASCPPGLYQT</td><td style="background-color: #f9f9f9;"></td><td>VPPEEHYQTF</td><td style="background-color: #f9f9f9;"></td><td>PIQDPDQMHS</td><td style="background-color: #f9f9f9;"></td><td>TSDPSHRSSS</td></tr>
<tr style="background-color: #eee;"><td>PELSEMLEYD</td><td style="background-color: #f9f9f9;"></td><td>RSHKSFPTDI</td><td style="background-color: #f9f9f9;"></td><td>SQMSPSSEHE</td><td style="background-color: #f9f9f9;"></td><td>VWQTVISPDL</td><td style="background-color: #f9f9f9;"></td><td>SQVTLSPELS</td></tr>
<tr style="background-color: #eee;"><td>QTNLSPDLSH</td><td style="background-color: #f9f9f9;"></td><td>TTLSPELIQR</td><td style="background-color: #f9f9f9;"></td><td>NLSPALGQMP</td><td style="background-color: #f9f9f9;"></td><td>ISPDLSHTTL</td><td style="background-color: #f9f9f9;"></td><td>SPDLSHTTLS</td></tr>
<tr style="background-color: #eee;"><td>LDLSQTNLSP</td><td style="background-color: #f9f9f9;"></td><td>ELSQTNLSPA</td><td style="background-color: #f9f9f9;"></td><td>LGQMPLSPDL</td><td style="background-color: #f9f9f9;"></td><td>SHTTLSLDFS</td><td style="background-color: #f9f9f9;"></td><td>QTNLSPELSH</td></tr>
<tr style="background-color: #eee;"><td>MTLSPELSQT</td><td style="background-color: #f9f9f9;"></td><td>NLSPALGQMP</td><td style="background-color: #f9f9f9;"></td><td>ISPDLSHTTL</td><td style="background-color: #f9f9f9;"></td><td>SLDFSQTNLS</td><td style="background-color: #f9f9f9;"></td><td>PELSQTNLSP</td></tr>
<tr style="background-color: #eee;"><td>ALGQMPLSPD</td><td style="background-color: #f9f9f9;"></td><td>PSHTTLSLDL</td><td style="background-color: #f9f9f9;"></td><td>SQTNLSPELS</td><td style="background-color: #f9f9f9;"></td><td>QTNLSPDLSE</td><td style="background-color: #f9f9f9;"></td><td>MPLFADLSQI</td></tr>
<tr style="background-color: #eee;"><td>PLTPDLDQMT</td><td style="background-color: #f9f9f9;"></td><td>LSPDLGETDL</td><td style="background-color: #f9f9f9;"></td><td>SPNFGQMSLS</td><td style="background-color: #f9f9f9;"></td><td>PDLSQVTLSP</td><td style="background-color: #f9f9f9;"></td><td>DISDTTLLPD</td></tr>
<tr style="background-color: #eee;"><td>LSQISPPPDL</td><td style="background-color: #f9f9f9;"></td><td>DQIFYPSESS</td><td style="background-color: #f9f9f9;"></td><td>QSLLLQEFNE</td><td style="background-color: #f9f9f9;"></td><td>SFPYPDLGQM</td><td style="background-color: #f9f9f9;"></td><td>PSPSSPTLND</td></tr>
<tr style="background-color: #eee;"><td>TFLSKEFNPL</td><td style="background-color: #f9f9f9;"></td><td>VIVGLSKDGT</td><td style="background-color: #f9f9f9;"></td><td>DYIEIIPKEE</td><td style="background-color: #f9f9f9;"></td><td>VQSSEDDYAE</td><td style="background-color: #f9f9f9;"></td><td>IDYVPYDDPY</td></tr>
<tr style="background-color: #eee;"><td>KTDVRTNINS</td><td style="background-color: #f9f9f9;"></td><td>SRDPDNIAAW</td><td style="background-color: #f9f9f9;"></td><td>YLRSNNGNRR</td><td style="background-color: #f9f9f9;"></td><td>NYYIAAEEIS</td><td style="background-color: #f9f9f9;"></td><td>WDYSEFVQRE</td></tr>
<tr style="background-color: #eee;"><td>TDIEDSDDIP</td><td style="background-color: #f9f9f9;"></td><td>EDTTYKKVVF</td><td style="background-color: #f9f9f9;"></td><td>RKYLDSTFTK</td><td style="background-color: #f9f9f9;"></td><td>RDPRGEYEEH</td><td style="background-color: #f9f9f9;"></td><td>LGILGPIIRA</td></tr>
<tr style="background-color: #eee;"><td>EVDDVIQVRF</td><td style="background-color: #f9f9f9;"></td><td>KNLASRPYSL</td><td style="background-color: #f9f9f9;"></td><td>HAHGLSYEKS</td><td style="background-color: #f9f9f9;"></td><td>SEGKTYEDDS</td><td style="background-color: #f9f9f9;"></td><td>PEWFKEDNAV</td></tr>
<tr style="background-color: #eee;"><td>QPNSSYTYVW</td><td style="background-color: #f9f9f9;"></td><td>HATERSGPES</td><td style="background-color: #f9f9f9;"></td><td>PGSACRAWAY</td><td style="background-color: #f9f9f9;"></td><td>YSAVNPEKDI</td><td style="background-color: #f9f9f9;"></td><td>HSGLIGPLLI</td></tr>
<tr style="background-color: #eee;"><td>CQKGILHKDS</td><td style="background-color: #f9f9f9;"></td><td>NMPMDMREFV</td><td style="background-color: #f9f9f9;"></td><td>LLFMTFDEKK</td><td style="background-color: #f9f9f9;"></td><td>SWYYEKKSRS</td><td style="background-color: #f9f9f9;"></td><td>SWRLTSSEMK</td></tr>
<tr style="background-color: #eee;"><td>KSHEFHAING</td><td style="background-color: #f9f9f9;"></td><td>MIYSLPGLKM</td><td style="background-color: #f9f9f9;"></td><td>YEQEWVRLHL</td><td style="background-color: #f9f9f9;"></td><td>LNIGGSQDIH</td><td style="background-color: #f9f9f9;"></td><td>VVHFHGQTLL</td></tr>
<tr style="background-color: #eee;"><td>ENGNKQHQLG</td><td style="background-color: #f9f9f9;"></td><td>VWPLLPGSFK</td><td style="background-color: #f9f9f9;"></td><td>TLEMKASKPG</td><td style="background-color: #f9f9f9;"></td><td>WWLLNTEVGE</td><td style="background-color: #f9f9f9;"></td><td>NQRAGMQTPF</td></tr>
<tr style="background-color: #eee;"><td>LIMDRDCRMP</td><td style="background-color: #f9f9f9;"></td><td>MGLSTGIISD</td><td style="background-color: #f9f9f9;"></td><td>SQIKASEFLG</td><td style="background-color: #f9f9f9;"></td><td>YWEPRLARLN</td><td style="background-color: #f9f9f9;"></td><td>NGGSYNAWSV</td></tr>
<tr style="background-color: #eee;"><td>EKLAAEFASK</td><td style="background-color: #f9f9f9;"></td><td>PWIQVDMQKE</td><td style="background-color: #f9f9f9;"></td><td>VIITGIQTQG</td><td style="background-color: #f9f9f9;"></td><td>AKHYLKSCYT</td><td style="background-color: #f9f9f9;"></td><td>TEFYVAYSSN</td></tr>
<tr style="background-color: #eee;"><td>QINWQIFKGN</td><td style="background-color: #f9f9f9;"></td><td>STRNVMYFNG</td><td style="background-color: #f9f9f9;"></td><td>NSDASTIKEN</td><td style="background-color: #f9f9f9;"></td><td>QFDPPIVARY</td><td style="background-color: #f9f9f9;"></td><td>IRISPTRAYN</td></tr>
<tr style="background-color: #eee;"><td>RPTLRLELQG</td><td style="background-color: #f9f9f9;"></td><td>CEVNGCSTPL</td><td style="background-color: #f9f9f9;"></td><td>GMENGKIENK</td><td style="background-color: #f9f9f9;"></td><td>QITASSFKKS</td><td style="background-color: #f9f9f9;"></td><td>WWGDYWEPFR</td></tr>
<tr style="background-color: #eee;"><td>ARLNAQGRVN</td><td style="background-color: #f9f9f9;"></td><td>AWQAKANNNK</td><td style="background-color: #f9f9f9;"></td><td>QWLEIDLLKI</td><td style="background-color: #f9f9f9;"></td><td>KKITAIITQG</td><td style="background-color: #f9f9f9;"></td><td>CKSLSSEMYV</td></tr>
<tr style="background-color: #eee;"><td>KSYTIHYSEQ</td><td style="background-color: #f9f9f9;"></td><td>GVEWKPYRLK</td><td style="background-color: #f9f9f9;"></td><td>SSMVDKIFEG</td><td style="background-color: #f9f9f9;"></td><td>NTNTKGHVKN</td><td style="background-color: #f9f9f9;"></td><td>FFNPPIISRF</td></tr>
<tr style="background-color: #eee;"><td>IRVIPKTWNQ</td><td style="background-color: #f9f9f9;"></td><td>SIALRLELFG</td><td style="background-color: #f9f9f9;"></td><td>CDIY</td></tr>
</table>
 
==Struktura==
Protein faktora V sastoji se od šest domena: A1-A2-B-A3-C1-C2.
 
A domeni su [[homologija sekvence|homologni]] sa A domenima proteina koji vezuje [[bakar]] ni [[ceruloplazmin]]  i formiraju trouglastu strukturu kao u tom proteinu. Ion bakra je vezan na interfejsu A1-A3, a A3 je u interakciji sa plazmom.<ref>{{cite journal | vauthors = Villoutreix BO, Björn Dahlbäck | title = Structural investigation of the A domains of human blood coagulation factor V by molecular modeling | journal = Protein Science | volume = 7 | issue = 6 | pages = 1317–25 | date = juni 1998 | pmid = 9655335 | doi = 10.1002/pro.5560070607 | pmc=2144041}}</ref>
 
C-domeni pripadaju porodici [[fosfolipid]]-vezujućih [[diskoidinski domen|diskoidinskih domena]] (nije u vezi sa [[C2-domen]]om), a C2-domen posreduje u vezivanju membrane. B-domen [[C-terminal]]a deluje kao [[kofaktor (biohemija)|kofaktor]] za [[antikoagulans]]ni [[protein C]] aktivirajući [[protein S]].<ref name = "Thorelli1998">{{cite journal | vauthors = Thorelli E, Kaufman RJ, Dahlbäck B | title = The C-terminal region of the factor V B-domain is crucial for the anticoagulant activity of factor V | journal = The Journal of Biological Chemistry | volume = 273 | issue = 26 | pages = 16140–45 | date = juni 1998 | pmid = 9632668 | doi=10.1074/jbc.273.26.16140| doi-access = free }}</ref><ref>{{cite journal | vauthors = Macedo-Ribeiro S, Bode W, Huber R, Quinn-Allen MA, Kim SW, Ortel TL, Bourenkov GP, Bartunik HD, Stubbs MT, Kane WH, Fuentes-Prior P | title = Crystal structures of the membrane-binding C2 domain of human coagulation factor V | journal = Nature | volume = 402 | issue = 6760 | pages = 434–39 | date = novembar 1999 | pmid = 10586886 | doi = 10.1038/46594 | bibcode = 1999Natur.402..434M | s2cid = 4393638 }}</ref>
 
Aktivacija faktora V u faktor Va vrši se cijepanjem i oslobađanjem B-domena, nakon čega protein više ne pomaže u aktivaciji proteina C. Protein je sada podijeljen na teški lanac koji se sastoji od A1-A2 domena i lahki lanac, koji se sastoji od A3-C1-C2 domena. Oba nekovalentno formiraju kompleks na način ovisan o [[kalcij]]u. Ovaj kompleks je prokoagulantni faktor Va.<ref name="Thorelli1998"/>