PlantRegMap/PlantTFDB v5.0
Plant Transcription Factor Database
Previous version: v3.0 v4.0
Transcription Factor Information
Basic Information | Signature Domain | Sequence | 
Basic Information? help Back to Top
TF ID GRMZM2G015534_P01
Common Nameo2
Taxonomic ID
Taxonomic Lineage
cellular organisms; Eukaryota; Viridiplantae; Streptophyta; Streptophytina; Embryophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliophyta; Mesangiospermae; Liliopsida; Petrosaviidae; commelinids; Poales; Poaceae; PACMAD clade; Panicoideae; Andropogonodae; Andropogoneae; Tripsacinae; Zea
Family bZIP
Protein Properties Length: 456aa    MW: 49191.4 Da    PI: 4.7814
Description bZIP family protein
Gene Model
Gene Model ID Type Source Coding Sequence
GRMZM2G015534_P01genomeMaizeSequenceView CDS
Signature Domain? help Back to Top
Signature Domain
No. Domain Score E-value Start End HMM Start HMM End
             bZIP_1   5 krerrkqkNReAArrsRqRKkaeieeLeekvkeLeaeNkaLkkeleelkkevakl 59 
                        ++ +rk++NRe+ArrsR RK a ++eLe+ v++L+aeN+ L  ++  l++++   
                        5789*********************************************998765 PP

Protein Features ? help Back to Top
3D Structure
Database Entry ID E-value Start End InterPro ID Description
SMARTSM003384.5E-20243307IPR004827Basic-leucine zipper domain
PROSITE profilePS5021711.783245299IPR004827Basic-leucine zipper domain
Gene3DG3DSA: hitNo description
SuperFamilySSF579593.25E-10247298No hitNo description
PfamPF001705.4E-11247299IPR004827Basic-leucine zipper domain
CDDcd147022.37E-21249299No hitNo description
PROSITE patternPS000360250265IPR004827Basic-leucine zipper domain
PfamPF124981.5E-21314428IPR020983Basic leucine-zipper, C-terminal
Gene Ontology ? help Back to Top
GO Term GO Category GO Description
GO:0006355Biological Processregulation of transcription, DNA-templated
GO:0003700Molecular Functiontranscription factor activity, sequence-specific DNA binding
GO:0043565Molecular Functionsequence-specific DNA binding
Plant Ontology ? help Back to Top
PO Term PO Category PO Description
PO:0006310anatomytassel floret
PO:0006339anatomyjuvenile vascular leaf
PO:0006340anatomyadult vascular leaf
PO:0006341anatomyprimary shoot system
PO:0006354anatomyear floret
PO:0006505anatomycentral spike of ear inflorescence
PO:0008018anatomytransition vascular leaf
PO:0009009anatomyplant embryo
PO:0009025anatomyvascular leaf
PO:0009054anatomyinflorescence bract
PO:0020040anatomyleaf base
PO:0020126anatomytassel inflorescence
PO:0020127anatomyprimary root
PO:0020136anatomyear inflorescence
PO:0020142anatomystem internode
PO:0025142anatomyleaf tip
PO:0001007developmental stagepollen development stage
PO:0001009developmental stageD pollen mother cell meiosis stage
PO:0001052developmental stagevascular leaf expansion stage
PO:0001053developmental stagevascular leaf post-expansion stage
PO:0001083developmental stageinflorescence development stage
PO:0001094developmental stageplant embryo coleoptilar stage
PO:0001095developmental stageplant embryo true leaf formation stage
PO:0001180developmental stageplant proembryo stage
PO:0007001developmental stageearly whole plant fruit ripening stage
PO:0007003developmental stageIL.03 full inflorescence length reached stage
PO:0007006developmental stageIL.00 inflorescence just visible stage
PO:0007016developmental stagewhole plant flowering stage
PO:0007026developmental stageFL.00 first flower(s) open stage
PO:0007031developmental stagemid whole plant fruit ripening stage
PO:0007032developmental stagewhole plant fruit formation stage up to 10%
PO:0007063developmental stageLP.07 seven leaves visible stage
PO:0007065developmental stageLP.05 five leaves visible stage
PO:0007072developmental stageLP.18 eighteen leaves visible stage
PO:0007094developmental stageLP.01 one leaf visible stage
PO:0007101developmental stageLP.09 nine leaves visible stage
PO:0007104developmental stageLP.15 fifteen leaves visible stage
PO:0007106developmental stageLP.03 three leaves visible stage
PO:0007112developmental stage1 main shoot growth stage
PO:0007116developmental stageLP.11 eleven leaves visible stage
PO:0007633developmental stageendosperm development stage
PO:0021004developmental stageinflorescence initiation stage
Sequence ? help Back to Top
Protein Sequence    Length: 456 aa     Download sequence    Send to blast
Nucleic Localization Signal ? help Back to Top
No. Start End Sequence
Expression -- UniGene ? help Back to Top
UniGene ID E-value Expressed in
Expression -- Microarray ? help Back to Top
Source ID
Expression AtlasGRMZM2G015534
Expression -- Description ? help Back to Top
Source Description
UniprotTISSUE SPECIFICITY: Seed endosperm. {ECO:0000269|PubMed:9207153}.
Functional Description ? help Back to Top
Source Description
UniProtInvolved in the regulation of the endosperm-specific production of albumin b-32 and other zein proteins. It is a trans-acting transcriptional activator that binds to the consensus sequence 5'-GATGAYRTGR-3'. {ECO:0000269|PubMed:2001677}.
Function -- GeneRIF ? help Back to Top
  1. molecular evolution of the Opaque-2 gene was investigated in connection with its possible involvement in the domestication process [Opaque-2]
    [PMID: 16132467]
  2. This study investigated the phosphorylation extent of wild-type O2 and mutant-defective or mutant-truncated o2 polypeptides in endosperm cells, their subcellular localization, participation in complex formation, and involvement in functional activity.
    [PMID: 17827273]
  3. Several of the genes are associated with ethylene and ABA signaling and suggest a potential linkage of o2 endosperm modification with programmed cell death
    [PMID: 18427771]
  4. the frequency of heterofertilization of opaque-2 (o2) kernels in maize
    [PMID: 19076690]
  5. Polymorphisms in the Opaque2 coding sequence and several polymorphisms in the CyPPDK1 promoter nonadditively interact to modify both lysine content and the protein-versus-starch balance in Zea mays.
    [PMID: 19329568]
  6. O2 mediated transcriptional activation occurs in two phases, first a potentiated and second a transcriptional activated phase, both characterized by a specific profile of chromatin modifications.
    [PMID: 19482970]
  7. The segmental duplication of Opaque-2 gene is not only found in rice, but also in sorghum, which split from maize 11.9 million years ago.
    [PMID: 19825579]
  8. o2 kernels had greater transcriptional changes than transgenic zein reduction kernels in general.
    [PMID: 20473554]
  9. Pleiotropic effects were less evident in the Opaque-7 mutant, but severe in the Opaque-2 and o2o7 backgrounds, with large changes in gene expression patterns, affecting a broad range of kernel-expressed genes.
    [PMID: 21241522]
  10. Our study suggests that a Taxilin-mediated change in sub-cellular distribution of ZmO2 may have important functional consequences for ZmO2 activity.
    [PMID: 22937104]
  11. In silico dissection of the most significantly changed proteins revealed novel qualitative changes in lysine abundance contributing to the overall lysine increase and the nutritional rebalancing of the o2 and fl2 endosperm.
    [PMID: 26712829]
  12. The protein encoded by this gene physically interacts with the MADS47 protein (Gene:542034).
    [PMID: 27077660]
  13. This study gives us an intriguing insight into the metabolism changes in endosperm of waxy maize introgressed with opaque2.
    [PMID: 27391593]
  14. In the presence of O2, the suppression of OHPs(OHP1 and OHP2) did not cause a significant reduction in the transcription of alpha-zein genes, but in the absence of O2, OHPs were critical for the expression of residual levels of alpha-zeins
    [PMID: 27474726]
  15. o2 and Pbf RNA interference may affect the levels of some other transcription factor(s) or mRNA regulatory factor(s) that in turn would affect the transcript and protein levels of SSIIa and SBEI.
    [PMID: 27621432]
  16. recessive opaque2 (o2) allele that confers enhanced endosperm lysine and tryptophan, was introgressed using marker-assisted backcross breeding into three normal inbred lines
    [PMID: 29666347]
  17. The opaque 2 gene regulated multiple metabolic pathways related to biological processes (BP) and molecular function (MP) during waxy maize endosperm development. In particular, in the o2o2wxwx lines, the two genes that encode the EF-1alpha and LHT1 were up-regulated, but the gene that encodes sulfur-rich proteins was down-regulated, raising the grain lysine content.
    [PMID: 30764507]
Cis-element ? help Back to Top
Regulation -- PlantRegMap ? help Back to Top
Source Upstream Regulator Target Gene
Annotation -- Nucleotide ? help Back to Top
Source Hit ID E-value Description
GenBankBT0360230.0BT036023.1 Zea mays full-length cDNA clone ZM_BFb0092F08 mRNA, complete cds.
Annotation -- Protein ? help Back to Top
Source Hit ID E-value Description
RefseqXP_008651859.10.0regulatory protein opaque-2 isoform X1
SwissprotP129590.0OP2_MAIZE; Regulatory protein opaque-2
TrEMBLA0A1D6HTP70.0A0A1D6HTP7_MAIZE; Regulatory protein opaque-2
STRINGGRMZM2G015534_P010.0(Zea mays)
Orthologous Group ? help Back to Top
LineageOrthologous Group IDTaxa NumberGene Number
Representative plantOGRP1727523
Best hit in Arabidopsis thaliana ? help Back to Top
Hit ID E-value Description
AT5G24800.11e-19basic leucine zipper 9
Publications ? help Back to Top
  1. de Souza Filho GA, et al.
    Identification of a DNA-binding factor that recognizes an alpha-coixin promoter and interacts with a Coix Opaque-2 like protein.
    Plant Mol. Biol., 1999. 39(1): p. 95-104
  2. Burnett RJ,Larkins BA
    Opaque2 modifiers alter transcription of the 27-kDa gamma-zein genes in maize.
    Mol. Gen. Genet., 1999. 261(6): p. 908-16
  3. Gaziola SA,Alessi ES,Guimaraes PE,Damerval C,Azevedo RA
    Quality protein maize: a biochemical study of enzymes involved in lysine metabolism.
    J. Agric. Food Chem., 1999. 47(3): p. 1268-75
  4. Ciceri P,Locatelli F,Genga A,Viotti A,Schmidt RJ
    The activity of the maize Opaque2 transcriptional activator is regulated diurnally.
    Plant Physiol., 1999. 121(4): p. 1321-8
  5. Ciceri P, et al.
    Specific combinations of zein genes and genetic backgrounds influence the transcription of the heavy-chain zein genes in maize opaque-2 endosperms.
    Plant Physiol., 2000. 124(1): p. 451-60
  6. Wang X,Larkins BA
    Genetic analysis of amino acid accumulation in opaque-2 maize endosperm.
    Plant Physiol., 2001. 125(4): p. 1766-77
  7. Varagona MJ,Schmidt RJ,Raikhel NV
    Nuclear localization signal(s) required for nuclear targeting of the maize regulatory protein Opaque-2.
    Plant Cell, 1992. 4(10): p. 1213-27
  8. Bhat RA,Borst JW,Riehl M,Thompson RD
    Interaction of maize Opaque-2 and the transcriptional co-activators GCN5 and ADA2, in the modulation of transcriptional activity.
    Plant Mol. Biol., 2004. 55(2): p. 239-52
  9. Henry AM,Manicacci D,Falque M,Damerval C
    Molecular evolution of the Opaque-2 gene in Zea mays L.
    J. Mol. Evol., 2005. 61(4): p. 551-8
  10. Gavazzi F,Lazzari B,Ciceri P,Gianazza E,Viotti A
    Wild-type opaque2 and defective opaque2 polypeptides form complexes in maize endosperm cells and bind the opaque2-zein target site.
    Plant Physiol., 2007. 145(3): p. 933-45
  11. Holding DR, et al.
    Genetic analysis of opaque2 modifier loci in quality protein maize.
    Theor. Appl. Genet., 2008. 117(2): p. 157-70
  12. Yang W,Zheng Y,Wu J
    Heterofertilization of the opaque-2 endosperm in maize.
    Hereditas, 2008. 145(5): p. 225-30
  13. Hasjim J,Srichuwong S,Scott MP,Jane JL
    Kernel composition, starch structure, and enzyme digestibility of opaque-2 maize and quality protein maize.
    J. Agric. Food Chem., 2009. 57(5): p. 2049-55
  14. Manicacci D, et al.
    Epistatic interactions between Opaque2 transcriptional activator and its target gene CyPPDK1 control kernel trait variation in maize.
    Plant Physiol., 2009. 150(1): p. 506-20
  15. Locatelli S,Piatti P,Motto M,Rossi V
    Chromatin and DNA modifications in the Opaque2-mediated regulation of gene transcription during maize endosperm development.
    Plant Cell, 2009. 21(5): p. 1410-27
  16. Xu JH,Messing J
    Diverged copies of the seed regulatory Opaque-2 gene by a segmental duplication in the progenitor genome of rice, sorghum, and maize.
    Mol Plant, 2008. 1(5): p. 760-9
  17. Lohmer S, et al.
    The maize regulatory locus Opaque-2 encodes a DNA-binding protein which activates the transcription of the b-32 gene.
    EMBO J., 1991. 10(3): p. 617-24
  18. Frizzi A, et al.
    Compositional and transcriptional analyses of reduced zein kernels derived from the opaque2 mutation and RNAi suppression.
    Plant Mol. Biol., 2010. 73(4-5): p. 569-85
  19. Hartings H,Lauria M,Lazzaroni N,Pirona R,Motto M
    The Zea mays mutants opaque-2 and opaque-7 disclose extensive changes in endosperm metabolism as revealed by protein, amino acid, and transcriptome-wide analyses.
    BMC Genomics, 2011. 12: p. 41
  20. Zhang N, et al.
    Zea mays Taxilin protein negatively regulates opaque-2 transcriptional activity by causing a change in its sub-cellular distribution.
    PLoS ONE, 2012. 7(8): p. e43822
  21. Schmidt RJ,Burr FA,Aukerman MJ,Burr B
    Maize regulatory gene opaque-2 encodes a protein with a "leucine-zipper" motif that binds to zein DNA.
    Proc. Natl. Acad. Sci. U.S.A., 1990. 87(1): p. 46-50
  22. Hartings H, et al.
    The O2 gene which regulates zein deposition in maize endosperm encodes a protein with structural homologies to transcriptional activators.
    EMBO J., 1989. 8(10): p. 2795-801
  23. Zhang Z,Yang J,Wu Y
    Transcriptional Regulation of Zein Gene Expression in Maize through the Additive and Synergistic Action of opaque2, Prolamine-Box Binding Factor, and O2 Heterodimerizing Proteins.
    Plant Cell, 2015. 27(4): p. 1162-72
  24. Morton KJ,Jia S,Zhang C,Holding DR
    Proteomic profiling of maize opaque endosperm mutants reveals selective accumulation of lysine-enriched proteins.
    J. Exp. Bot., 2016. 67(5): p. 1381-96
  25. Qiao Z, et al.
    ZmMADS47 Regulates Zein Gene Transcription through Interaction with Opaque2.
    PLoS Genet., 2016. 12(4): p. e1005991
  26. Zhou Z, et al.
    Introgression of opaque2 into Waxy Maize Causes Extensive Biochemical and Proteomic Changes in Endosperm.
    PLoS ONE, 2016. 11(7): p. e0158971
  27. Yang J,Ji C,Wu Y
    Divergent Transactivation of Maize Storage Protein Zein Genes by the Transcription Factors Opaque2 and OHPs.
    Genetics, 2016. 204(2): p. 581-591
  28. Zhang Z,Zheng X,Yang J,Messing J,Wu Y
    Maize endosperm-specific transcription factors O2 and PBF network the regulation of protein and starch synthesis.
    Proc. Natl. Acad. Sci. U.S.A., 2016. 113(39): p. 10842-7
  29. Maddaloni M, et al.
    The sequence of the zein regulatory gene opaque-2 (O2) of Zea Mays.
    Nucleic Acids Res., 1989. 17(18): p. 7532
  30. Hossain F, et al.
    Marker-assisted introgression of opaque2 allele for rapid conversion of elite hybrids into quality protein maize.
    J. Genet., 2018. 97(1): p. 287-298
  31. Wang W, et al.
    Molecular Mechanisms Underlying Increase in Lysine Content of Waxy Maize through the Introgression of the opaque2 Allele.
    Int J Mol Sci, 2019.
  32. Gupta HO,Lodha ML,Rastogi DK,Singh J,Mehta SL
    Nutritional evaluation of hard endosperm opaque-2 maize (Zea mays L.).
    J. Agric. Food Chem., 1979 Mar-Apr. 27(2): p. 390-2
  33. Reddy V,Gupta CP
    Treatment of kwashiorkor with opaque-2 maize.
    Am. J. Clin. Nutr., 1974. 27(2): p. 122-4
  34. Quicke GV,Gevers HO
    Higher lysine levels and improved protein quality of opaque-2 maize.
    S. Afr. Med. J., 1972. 46(42): p. 1579-84
  35. Pradilla AG,Francis CA,Linares FA
    Studies on protein quality of flint phenotypes of opaque-2 modified maize.
    Arch Latinoam Nutr, 1973. 23(2): p. 217-23
  36. Ahuja VP,Srivastava KN,Austin A,Naik MS
    Changes in different protein fractions and their amino acid composition of the endosperm of opaque-2 composite maize, Shakti, during maturation.
    Indian J. Biochem. Biophys., 1973. 10(1): p. 48-50
  37. Gupta HO,Lodha ML,Mehta SL,Rastogi DK,Singh J
    Effect of amino acid(s) and pulse supplementation on nutritional quality of normal and modified opaque-2 maize (Zea mays L.).
    J. Agric. Food Chem., 1979 Jul-Aug. 27(4): p. 787-90
  38. Dalby A,Davies II
    Ribonuclease activity in the developing seeds of normal and opaque-2 maize.
    Science, 1967. 155(3769): p. 1573-5
  39. Lee L,Tsai CY
    Zein synthesis in the embryo and endosperm of maize mutants.
    Biochem. Genet., 1984. 22(7-8): p. 729-37
  40. Fuwa H,Glover DV,Sugimoto Y,Tanaka M
    Comparative susceptibility to amylases of starch granules of several single endosperm mutants representative of floury-opaque, starch-deficient, and modified starch types and their double-mutant combinations with opaque-2 in four inbred lines of maize.
    J. Nutr. Sci. Vitaminol., 1978. 24(4): p. 437-48
  41. Tsai CY,Larkins BA,Glover DV
    Interaction of the opaque-2 gene with starch-forming mutant genes on the synthesis of zein in maize endosperm.
    Biochem. Genet., 1978. 16(9-10): p. 883-96
  42. Michel D, et al.
    Insertion mutations at the maize Opaque2 locus induced by transposable element families Ac, En/Spm and Bg.
    Mol. Gen. Genet., 1995. 248(3): p. 287-92
  43. Lopes MA,Takasaki K,Bostwick DE,Helentjaris T,Larkins BA
    Identification of two opaque2 modifier loci in quality protein maize.
    Mol. Gen. Genet., 1995. 247(5): p. 603-13
  44. Cord Neto G, et al.
    The involvement of Opaque 2 on beta-prolamin gene regulation in maize and Coix suggests a more general role for this transcriptional activator.
    Plant Mol. Biol., 1995. 27(5): p. 1015-29
  45. Dannenhoffer JM,Bostwick DE,Or E,Larkins BA
    opaque-15, a maize mutation with properties of a defective opaque-2 modifier.
    Proc. Natl. Acad. Sci. U.S.A., 1995. 92(6): p. 1931-5
  46. Aukerman MJ,Schmidt RJ
    A 168 bp derivative of Suppressor-mutator/Enhancer is responsible for the maize o2-23 mutation.
    Plant Mol. Biol., 1993. 21(2): p. 355-62
  47. Varagona MJ,Raikhel NV
    The basic domain in the bZIP regulatory protein Opaque2 serves two independent functions: DNA binding and nuclear localization.
    Plant J., 1994. 5(2): p. 207-14
  48. Michel D,Salamini F,Motto M,Döring HP
    An unstable allele at the maize Opaque2 locus is caused by the insertion of a double Ac element.
    Mol. Gen. Genet., 1994. 243(3): p. 334-42
  49. Habben JE,Kirleis AW,Larkins BA
    The origin of lysine-containing proteins in opaque-2 maize endosperm.
    Plant Mol. Biol., 1993. 23(4): p. 825-38
  50. Maddaloni M, et al.
    The transcriptional activator Opaque-2 controls the expression of a cytosolic form of pyruvate orthophosphate dikinase-1 in maize endosperms.
    Mol. Gen. Genet., 1996. 250(5): p. 647-54
  51. Gallusci P,Varotto S,Matsuoko M,Maddaloni M,Thompson RD
    Regulation of cytosolic pyruvate, orthophosphate dikinase expression in developing maize endosperm.
    Plant Mol. Biol., 1996. 31(1): p. 45-55
  52. Pysh LD,Schmidt RJ
    Characterization of the maize OHP1 gene: evidence of gene copy variability among inbreds.
    Gene, 1996. 177(1-2): p. 203-8
  53. Rossi V,Motto M,Pellegrini L
    Analysis of the methylation pattern of the maize opaque-2 (O2) promoter and in vitro binding studies indicate that the O2 B-Zip protein and other endosperm factors can bind to methylated target sequences.
    J. Biol. Chem., 1997. 272(21): p. 13758-65
  54. Vicente-Carbajosa J,Moose SP,Parsons RL,Schmidt RJ
    A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2.
    Proc. Natl. Acad. Sci. U.S.A., 1997. 94(14): p. 7685-90