Protein Tags

VectorBuilder offers many popular vector components that users can choose from when designing their vectors. The tables below provide detailed information on these popular components, which are listed separately by category.
Epitope Tags
Name Description Application Notes References Sequence
FLAG FLAG epitope tag Facilitates antibody binding of tagged protein. J Biochem Biophys Methods. 49:455 (2001); Appl Microbiol Biotechnol. 60:523 (2003) View
3xFLAG 3 tandem FLAG epitope tag Facilitates antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
HA Hemagglutinin epitope tag Facilitates antibody binding of tagged protein. Nature. 443:230 (2006) View
Myc c-Myc epitope tag Facilitates antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
V5 V5 epitope tag Facilitates antibody binding of tagged protein. J Biol Chem. 282:20799 (2007) View
OVA(257-264) H-2Kb-restricted OVA MHC class I epitope Allows detection of a strong CD8+ cytolytic T cell response. Eur J Immunol. 21:2891 (1991); J Immunol. 150:1212 (1993) View
OVA(323-339) I-Ad-restricted OVA MHC class II epitope Allows studying the nature of class II MHC-peptide binding and T-cell activation. Biochemistry. 38:16663 (1999); J Immunol. 171:1999 (2003) View
10xGCN4_v4 The v4 version of the GCN4 peptide array with 10 copies of the peptide binding site, also know as SunTag10x_v4 Allows tagged proteins to be recognized by the GCN4 scFv antibody. Cell. 159: 635 (2014) View
Purification Tags
Name Description Application Notes References Sequence
6xHis 6 tandem histidine tag Facilitates purification by nickel or cobalt matrix and antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
10xHis 10 tandem histidine tag Facilitates purification by nickel or cobalt matrix and antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
Strep-tag_II Strep-tag II Facilitates purification by Strep-Tactin (modified streptavidin) matrix and antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
Twin-Strep-tag 2 tandem Strep-tag II linked with 3xGGGS Facilitates purification by Strep-Tactin (modified streptavidin) matrix and antibody binding of tagged protein. Protein Expr Purif. 92:54 (2013) View
S-tag S-tag Facilitates purification by S-protein matrix and antibody binding of tagged protein. Appl Microbiol Biotechnol. 60:523 (2003) View
MBP Maltose-binding protein Facilitates purification by amylose matrix and antibody binding of tagged protein; increases the solubility of tagged protein in bacteria. Appl Microbiol Biotechnol. 60:523 (2003) View
GST Glutathione S-transferase Facilitates purification by glutathione matrix and antibody binding of tagged protein; helps to stabilize tagged protein and protect it against intracellular protease cleavage. Appl Microbiol Biotechnol. 60:523 (2003) View
Avi Avi tag Facilitates biotinylation of tagged protein by the enzyme BirA so the protein can be isolated by streptavidin. Protein Sci. 8:921 (1999); Methods Mol Biol. 1266: 171 (2015) View
Halo HaloTag7 Increases expression and solubility of tagged protein; enables covalent, efficient and specific capture of a protein of interest onto HaloLink™ Resin; high yield and purity. Protein Expr Purif. 68:110 (2009) View
Halo-TEV HaloTag7 linked with TEV site Increases expression and solubility of tagged protein; enables covalent, efficient and specific capture of a protein of interest onto HaloLink™ Resin; high yield and purity; can be removed by TEV protease; N-terminal tag. Protein Expr Purif. 68:110 (2009) View
SUMO Small ubiquitin-like modifier tag Facilitates purification by enhancing stability and solubility of tagged proteins; can be specifically recognized by SUMO proteases. Protein Sci.22(11):1466-77 (2013) View
hIgG-Fc The constant region (CH2 and CH3 domains) of human immunoglobulin heavy chain Increases protein yield; allows rapid and simple detection of protein expression; enables simple protein G/A affinity chromatography based purification of Fc-tagged proteins. EMBO Mol Med. 4:1015 (2012); J Biomed Res. 30: 209 (2016) View
mlgG-Fc The constant region (CH2 and CH3 domains) of mouse immunoglobulin heavy chain Increases protein yield; allows rapid and simple detection of protein expression; enables simple protein G affinity chromatography based purification of Fc-tagged proteins. EMBO Mol Med. 4:1015 (2012); Sci Rep. 6:30171 (2016) View
Protease Cleavage Sites
Name Description Application Notes References Sequence
EK Bovine enterokinase cleavage site Cleaved by enterokinase, which cuts after lysine in the recognition sequence DDDDK. Appl Microbiol Biotechnol. 60:523 (2003) View
TEV Tobacco etch virus protease cleavage site Cleaved by tobacco etch virus protease, which cuts after glutamine in the recognition sequence EXXYXQ(G/S) where X can be any amino acid. Appl Microbiol Biotechnol. 60:523 (2003) View
Thrombin Thrombin cleavage site Cleaved by thrombin, which cuts after the fourth residue in the recognition sequence XXP(R/K)XX where XX on the N end are hydrophobic residues and XX on the C end are non-acidic residues. Appl Microbiol Biotechnol. 60:523 (2003) View
Factor-Xa Factor Xa cleavage site Cleaved by factor Xa, which cuts after arginine in the recognition sequence I(E/D)GR. Appl Microbiol Biotechnol. 60:523 (2003) View
HRV3C Human rhinovirus 3C protease site Cleaved by human rhinovirus 3C protease, the cleavage site is between Gln and Gly in the recognition sequences LEVLFQ↓GP. Cell.168(3):427-441 (2017) View
Signal Peptides (for directing subcellular localization of proteins, such as nuclear localization, membrane localization, secretion, etc.)
Name Description Application Notes References Sequence
SV40-NLS Simian virus 40 nuclear localization signal Directs nuclear localization of tagged protein. Cell. 39:499 (1984) View
3xNLS 3 tandem simian virus 40 nuclear localization signal Directs nuclear localization of tagged protein. J Immunol. 182: 3173 (2009) View
cMYC-NLS Nuclear localization signal of human c-MYC gene Directs nuclear localization of tagged protein. Mol Cell Biol. 8:4048 (1988); Bioconjug Chem. 26: 1004 (2015) View
BPSV40-NLS A classical nuclear localization signal (NLS) consists of two clusters of basic residues separated by 10–12 residues (bipartite), NLS-containing cargoes are imported by a heterodimeric import receptor complex composed of importin α and importin β Directs nuclear localization of tagged protein. J Biol Chem. 276:1317 (2001); Biophys J. 96:3840 (2009); Nature. 540:144 (2016); Nat Methods. 16:887-893 (2019) View
MITO Mitochondrial targeting sequence from human cytochrome c oxidase subunit VIII gene Directs tagged protein to the intermembrane space of mitochondria. Nature. 358:325 (1992); Proc Natl Acad Sci U S A. 96: 11752 (1999) View
Igκ-sig Murine Ig kappa chain leader sequence Directs tagged protein to the secretory pathway. J Immunol Methods. 152:89 (1992) View
α-Factor Yeast pheromone α-factor leader sequence Directs export of tagged protein in yeast into culture medium. Gene. 54:175 (1987) View
PelB Pectate lyase B leader sequence Directs tagged protein to the bacterial periplasm, where the sequence is removed by a signal peptidase. Protein Expr Purif. 54:227 (2007) View
NES Nuclear export signal Directs nuclear export of tagged protein. PLoS One.10:e0137652 (2015) View
Lyn N-terminal myristoylation and palmitoylation sequence from Lyn, a Src family tyrosine kinase Anchors the tagged protein to the plasma membrane. J Neurosci Methods. 93:37 (1999); J Cell Biol. 174:255 (2006) View
SNAP25 A protein which is synthesized on free ribosomes and recruited to the inner surface of plasma membrane after the palimitoylation of specific cystesine residues Directs the tagged proteins to the inner surface of plasma membrane. EMBO J. 16:1575 (1997) View
GPI Plasma membrane glycosylphosphatidylinositol anchoring signal Anchors glycoprotein to the plasma membrane; helps increase the mobility of membrane proteins therefore supporting signal transduction and cellular transport; plays an important role in creating antigens on cell surface. Genesis. 44:202 (2006) View
TMD-ST Transmembrane domain of rat liver sialyltransferase Directs the tagged protein to Golgi. J Biol Chem. 270:5483 (1995) View
PDGFR Platelet-derived growth factor receptor beta transmembrane domain Anchors the tagged protein to the extracellular side of plasma membrane for displaying, usually works with secretory signal peptide. Proc Natl Acad Sci U S A. 85:3435 (1988); J Biol Chem. 285:12268 (2010) View
GLuc Gaussia luciferase secretory signal peptide Allows the tagged protein to be secreted from cytosol. Microb Cell Fact. 14:20 (2015) View
IL2-sig Homo sapiens interleukin 2, transcript variant X1, mRNA Facilitates secretion of proteins. Protein Expr Purif.118:105-12(2016) View
HA-sig The cleavable signal sequence of influenza hemagglutinin Enhances localization of proteins to the endoplasmic reticulum membrane or plasma membrane. J Biol Chem. 267:21995 (1992); Biochem Biophys Res Commun. 409:544 (2011) View
Detection Tags
Name Description Application Notes References Sequence
TC Tetracysteine tag Facilitates detection of tagged protein by biarsenical compounds such as FlAsH-EDT2 and ReAsH-EDT2, which turn fluorescent upon binding to the tag. Nat Protoc. 5: 1666 (2010) View
ProS2 Protein S of Myxococcus xanthus Facilitates detection of tagged protein by anti-ProS2 antibody; increases the solubility and stability of tagged protein in bacteria. J Mol Biol. 286:1533 (1999) View
TF E.coli trigger factor, a ribosome-associated chaperone Assists protein folding; facilitates detection of tagged protein by anti-trigger factor antibody; increases the solubility of tagged protein. Biochim Biophys Acta. 1803:650 (2010) View
Lifeact A 17-aa F-actin-binding sequence derived from Saccharomyces cerevisiae Allows visualization of F-actin dynamics in cells; can be used as a universal marker for F-actin imaging or as an alternative to phalloidin. Nat Methods. 5:605 (2008) View
SNAP A 20 kDa engineered variant of the human DNA repair protein O-6-alkylguanine-DNA alkyltransferase, optimized for mammalian expression Allows to observe localization and translocation of SNAP-tag fusion proteins; reacts specifically and rapidly with benzylguanine (BG) and benzylchloropyrimidine (CP) derivatives, leading to irreversible covalent labeling of the SNAP-tag with a wide variety of synthetic probes in live cells. CLIP and SNAP fusion proteins can be simultaneously and specifically labeled with different synthetic probes within cells. Nat Biotechnol. 21:86 (2003); Methods Mol Biol. 1266:107 (2015) View
CLIP An engineered variant of the human DNA repair protein O-6-alkylguanine-DNA alkyltransferase, optimized for mammalian expression Allows to observe localization and translocation of CLIP-tag fusion proteins; reacts specifically and rapidly with O2-benzylcytosine (BC) derivatives, leading to irreversible covalent labeling of the CLIP-tag with a wide variety of synthetic probes in live cells. CLIP and SNAP fusion proteins can be simultaneously and specifically labeled with different synthetic probes within cells. Chem Biol. 15:128 (2008) View
ACP Acyl carrier protein of E. coli Allows to observe localization and translocation of ACP-tag fusion cell surface proteins which are specifically labeled with CoA derivatives through post-translational modifications catalyzed by the phosphopantetheinyl transferase AcpS. J Am Chem Soc. 126:8896 (2004) View
HiBiT A small 11 amino acid peptide that binds LgBiT with high affinity Facilitates detection and monitoring of tagged endogenous protein in live cells; capable of producing highly active Nanoluc luciferase through high affinity complementation with LgBiT. Biochem Biophys Rep. 12: 40 (2017); Chem Biol. 13:467 (2018) View
Cell-Penetrating Peptides
Name Description Application Notes References Sequence
TAT Amino acids 48–60 of transactivator of transcription protein (Tat) from human immunodeficiency virus type 1 (HIV-1). Directs tagged protein to pass through the plasma membrane of mammalian cells. J Biol Chem. 276:5836 (2001); ACS Nano. 8:1972 (2014); Biomol Concepts. 8:131 (2017) View
R8 Octaarginine tag (8 tandem argenines). Directs tagged protein to pass through the plasma membrane of mammalian cells. J Biol Chem. 276:5836 (2001); ACS Nano. 8:1972 (2014); Biomol Concepts. 8:131 (2017) View
Regulatory Proteins
Name Description Application Notes References Sequence
VP16 VP16 transcriptional activator domain encoded by HSV Activates gene expression, commonly used with other DNA binding proteins. Cell. 149:1447 (2012) View
VP64 Tetrameric repeat of the minimal activation domain of VP16 Strongly activates gene expression, commonly used with other DNA binding proteins. Proc Natl Acad Sci U S A. 95: 14628 (1998); Proc Natl Acad Sci U S A. 97: 1495 (2000) View
KRAB Krüppel-associated box domain from human gene ZNF10 Inhibits gene expression, commonly used with other DNA binding proteins. Proc Natl Acad Sci U S A. 91:4509 (1994); Proc Natl Acad Sci U S A. 97: 1495 (2000) View
CAR-T Proteins
Name Description Application Notes References Sequence
CD8-leader Leader signal peptide of T-cell surface glycoprotein CD8 alpha chain Directs transport and localization of the protein to the T-cell surface. Cell. 64:891 (1991); WO2014055771A1; US20160185862A1; US10144770B2 View
CD8-hinge Hinge region of T-cell surface glycoprotein CD8 alpha chain Connects scFv and the transmembrane region; enhances tumor recognition efficiency; improves the expansion of CAR-T cells. Cell. 64:891 (1991); J Immunother. 28:203 (2005); BMJ Open. 6: e013904 (2016); J Hematol Oncol. 10: 68 (2017); Oncoimmunology. 7: e1368604 (2018) View
CD28-hinge Hinge region of the T-cell surface glycoprotein CD28 Connects scFv with the transmembrane region providing stability and flexibilty for efficient CAR expression and function; enhances efficiency of tumor recognition; improves expansion of CAR-T cells. J Immunother. 32:689 (2009); Mol Ther. 25:2452 (2017) View
CD8-TM Transmembrane region of T-cell surface glycoprotein CD8 alpha chain Anchors the CAR to the plasma membrane, bridges the extracellular hinge and antigen recognition domains with the intracellular signaling region. Cell. 64:891 (1991); BMJ Open. 6: e013904 (2016); Oncoimmunology. 7: e1368604 (2018); WO2014055771A1; US20100105136A1 View
CD28-TM Transmembrane region of T-cell-surface glycoprotein CD28 Anchors the CAR to the plasma membrane; enhances receptor expression and stability. Hum Gene Ther. 24:259 (2013); Cancer Res. 74:6383 (2014); WO2014055771A1; US10144770B2 View