ID O11883_HBV Unreviewed; 154 AA. AC O11883; DT 01-JUL-1997, integrated into UniProtKB/TrEMBL. DT 01-JUL-1997, sequence version 1. DT 24-JUL-2024, entry version 96. DE RecName: Full=Protein X {ECO:0000256|HAMAP-Rule:MF_04074, ECO:0000256|RuleBase:RU361181}; DE AltName: Full=HBx {ECO:0000256|HAMAP-Rule:MF_04074, ECO:0000256|RuleBase:RU361181}; DE AltName: Full=Peptide X {ECO:0000256|HAMAP-Rule:MF_04074, ECO:0000256|RuleBase:RU361181}; DE AltName: Full=pX {ECO:0000256|HAMAP-Rule:MF_04074, ECO:0000256|RuleBase:RU361181}; GN Name=X {ECO:0000256|HAMAP-Rule:MF_04074, GN ECO:0000256|RuleBase:RU361181, ECO:0000313|EMBL:AGA16743.1}; OS Hepatitis B virus (HBV). OC Viruses; Riboviria; Pararnavirae; Artverviricota; Revtraviricetes; OC Blubervirales; Hepadnaviridae; Orthohepadnavirus. OX NCBI_TaxID=10407 {ECO:0000313|EMBL:AAB59970.1}; OH NCBI_TaxID=9606; Homo sapiens (Human). OH NCBI_TaxID=9598; Pan troglodytes (Chimpanzee). RN [1] {ECO:0000313|EMBL:AAB59970.1} RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. RA Rao B.S., Casey J.L., Rinaudo J.S., Korba B.E.; RT "Complete nucleotide sequence of a molecular clone of hepatitis B virus RT from the 2.2.15 cell line."; RL Submitted (MAR-1997) to the EMBL/GenBank/DDBJ databases. RN [2] {ECO:0000313|EMBL:BAE93198.1, ECO:0000313|Proteomes:UP000133680} RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. RC STRAIN=Toshima 1 {ECO:0000313|EMBL:BAE93198.1}; RX PubMed=17191017; DOI=10.1159/000098241; RA Michitaka K., Horiike N., Duong T.N., Yagura M., Harada H., Shibayama T., RA Inui A., Fujisawa T., Matsuura K., Hiasa Y., Onji M.; RT "Heterogeneity of hepatitis B virus genotype D in Japan."; RL Intervirology 50:150-155(2007). RN [3] {ECO:0000313|Proteomes:UP000100826, ECO:0000313|Proteomes:UP000123655} RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. RC STRAIN=P11 {ECO:0000313|EMBL:AGA16743.1}, P16 RC {ECO:0000313|EMBL:AGA16771.1}, P17 {ECO:0000313|EMBL:AGA16778.1}, P19 RC {ECO:0000313|EMBL:AGA16785.1}, P24 {ECO:0000313|EMBL:AGA16799.1}, and RC P29 {ECO:0000313|EMBL:AGA16764.1}; RA Alestig E.; RT "Genetic diversity of genotype D3 in acute hepatitis B."; RL Submitted (OCT-2012) to the EMBL/GenBank/DDBJ databases. RN [4] {ECO:0000313|EMBL:AUG90794.1} RP NUCLEOTIDE SEQUENCE. RC STRAIN=AD38 {ECO:0000313|EMBL:AUG90794.1}; RA Burwitz B.J., Wettengel J.M., Muck-Hausl M.A., Ringelhan M., Ko C., RA Festag M.M., Hammond K.B., Northrup M., Bimber B.N., Jacob T., Reed J.S., RA Norris R., Park B., Moller-Tank S., Esser K., Greene J.M., Wu H.L., RA Abdulhaqq S., Webb G., Sutton W.F., Klug A., Swanson T., Legasse A.W., RA Vu T.Q., Asokan A., Haigwood N.L., Protzer U., Sacha J.B.; RT "Hepatocytic Expression of Human Sodium-Taurocholate Cotransporting RT Polypeptide Enables Hepatitis B Virus Infection of Macaques."; RL Submitted (SEP-2017) to the EMBL/GenBank/DDBJ databases. RN [5] {ECO:0000313|EMBL:QEX51856.1} RP NUCLEOTIDE SEQUENCE. RC STRAIN=HBV_occult_Arkh10 {ECO:0000313|EMBL:QEX51856.1}; RA Ostankova Y.V., Semenov A.V., Zueva E.B., Totolian A.A.; RT "Identification and molecular-genetic characteristics of the hepatitis B RT virus among HIV-infected patients in Arkhangelsk."; RL Vopr. Virusol. 0:0-0(2019). RN [6] {ECO:0000313|EMBL:QHB12472.1} RP NUCLEOTIDE SEQUENCE. RC STRAIN=954_ocHBVd_GC {ECO:0000313|EMBL:QHB12472.1}; RA Schemelev A.N., Ostankova Y.V., Zueva E.B., Semenov A.V.; RT "Characterization of HBV and HIV among HBV/HIV co-infected patients from RT Republic of Guinea."; RL Probl Osobo Opas Infekc 0:0-0(2020). CC -!- FUNCTION: Multifunctional protein that may modulate protein degradation CC pathways, apoptosis, transcription, signal transduction, cell cycle CC progress, and genetic stability by directly or indirectly interacting CC with host factors. {ECO:0000256|RuleBase:RU361181}. CC -!- FUNCTION: Multifunctional protein that plays a role in silencing host CC antiviral defenses and promoting viral transcription. Does not seem to CC be essential for HBV infection. May be directly involved in development CC of cirrhosis and liver cancer (hepatocellular carcinoma). Most of CC cytosolic activities involve modulation of cytosolic calcium. The CC effect on apoptosis is controversial depending on the cell types in CC which the studies have been conducted. May induce apoptosis by CC localizing in mitochondria and causing loss of mitochondrial membrane CC potential. May also modulate apoptosis by binding host CFLAR, a key CC regulator of the death-inducing signaling complex (DISC). Promotes CC viral transcription by using the host E3 ubiquitin ligase DDB1 to CC target the SMC5-SMC6 complex to proteasomal degradation. This host CC complex would otherwise bind to viral episomal DNA, and prevents its CC transcription. Moderately stimulates transcription of many different CC viral and cellular transcription elements. Promoters and enhancers CC stimulated by HBx contain DNA binding sites for NF-kappa-B, AP-1, AP-2, CC c-EBP, ATF/CREB, or the calcium-activated factor NF-AT. CC {ECO:0000256|HAMAP-Rule:MF_04074}. CC -!- SUBUNIT: May form homodimer. May interact with host CEBPA, CFLAR, CC CREB1, DDB1, E4F1, HBXIP, HSPD1/HSP60, NFKBIA, POLR2E and SMAD4. CC Interacts with host SMC5-SMC6 complex and induces its degradation. CC {ECO:0000256|HAMAP-Rule:MF_04074}. CC -!- SUBCELLULAR LOCATION: Host cytoplasm {ECO:0000256|HAMAP-Rule:MF_04074}. CC Host nucleus {ECO:0000256|HAMAP-Rule:MF_04074}. Host mitochondrion CC {ECO:0000256|HAMAP-Rule:MF_04074}. Note=Mainly cytoplasmic as only a CC fraction is detected in the nucleus. In cytoplasm, a minor fraction CC associates with mitochondria or proteasomes. {ECO:0000256|HAMAP- CC Rule:MF_04074}. CC -!- PTM: A fraction may be phosphorylated in insect cells and HepG2 cells, CC a human hepatoblastoma cell line. Phosphorylated in vitro by host CC protein kinase C or mitogen-activated protein kinase. N-acetylated in CC insect cells. {ECO:0000256|HAMAP-Rule:MF_04074}. CC -!- SIMILARITY: Belongs to the orthohepadnavirus protein X family. CC {ECO:0000256|HAMAP-Rule:MF_04074, ECO:0000256|RuleBase:RU361181}. CC --------------------------------------------------------------------------- CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms CC Distributed under the Creative Commons Attribution (CC BY 4.0) License CC --------------------------------------------------------------------------- DR EMBL; U95551; AAB59970.1; -; Genomic_DNA. DR EMBL; JX898686; AGA16743.1; -; Genomic_DNA. DR EMBL; JX898689; AGA16764.1; -; Genomic_DNA. DR EMBL; JX898690; AGA16771.1; -; Genomic_DNA. DR EMBL; JX898691; AGA16778.1; -; Genomic_DNA. DR EMBL; JX898692; AGA16785.1; -; Genomic_DNA. DR EMBL; JX898694; AGA16799.1; -; Genomic_DNA. DR EMBL; MF967563; AUG90794.1; -; Genomic_DNA. DR EMBL; AB210819; BAE93198.1; -; Genomic_DNA. DR EMBL; MK618438; QEX51856.1; -; Genomic_DNA. DR EMBL; MN507835; QHB12472.1; -; Genomic_DNA. DR Proteomes; UP000100826; Genome. DR Proteomes; UP000123655; Genome. DR Proteomes; UP000130756; Genome. DR Proteomes; UP000133680; Genome. DR Proteomes; UP000138899; Genome. DR Proteomes; UP000152046; Genome. DR Proteomes; UP000180829; Genome. DR Proteomes; UP000180868; Genome. DR GO; GO:0033650; C:host cell mitochondrion; IEA:UniProtKB-SubCell. DR GO; GO:0042025; C:host cell nucleus; IEA:UniProtKB-SubCell. DR GO; GO:0006915; P:apoptotic process; IEA:UniProtKB-KW. DR GO; GO:0006351; P:DNA-templated transcription; IEA:UniProtKB-UniRule. DR GO; GO:0039592; P:symbiont-mediated arrest of host cell cycle during G2/M transition; IEA:UniProtKB-UniRule. DR GO; GO:0019079; P:viral genome replication; IEA:UniProtKB-UniRule. DR HAMAP; MF_04074; HBV_X; 1. DR InterPro; IPR000236; Transactivation_prot_X. DR Pfam; PF00739; X; 1. PE 3: Inferred from homology; KW Activation of host NF-kappa-B by virus {ECO:0000256|HAMAP-Rule:MF_04074}; KW Activator {ECO:0000256|HAMAP-Rule:MF_04074}; KW Apoptosis {ECO:0000256|HAMAP-Rule:MF_04074}; KW Host cytoplasm {ECO:0000256|HAMAP-Rule:MF_04074, KW ECO:0000256|RuleBase:RU361181}; KW Host G2/M cell cycle arrest by virus {ECO:0000256|HAMAP-Rule:MF_04074}; KW Host mitochondrion {ECO:0000256|HAMAP-Rule:MF_04074, KW ECO:0000256|RuleBase:RU361181}; KW Host nucleus {ECO:0000256|HAMAP-Rule:MF_04074, KW ECO:0000256|RuleBase:RU361181}; KW Host-virus interaction {ECO:0000256|HAMAP-Rule:MF_04074, KW ECO:0000256|RuleBase:RU361181}; KW Modulation of host cell cycle by virus {ECO:0000256|HAMAP-Rule:MF_04074}; KW Transcription {ECO:0000256|HAMAP-Rule:MF_04074}; KW Transcription regulation {ECO:0000256|HAMAP-Rule:MF_04074}. FT REGION 68..117 FT /note="Mitochondrial targeting sequence" FT /evidence="ECO:0000256|HAMAP-Rule:MF_04074" SQ SEQUENCE 154 AA; 16611 MW; 895800BDF24CEA17 CRC64; MAARLCCQLD PARDVLCLRP VGAESCGRPF SGSLGTLSSP SPSAVPTDHG AHLSLRGLPV CAFSSAGPCA LRFTSARRME TTVNAHRMLP KVLHKRTLGL SAMSTTDLEA YFKDCLFKDW EELGEEIRLK VFVLGGCRHK LVCAPAPCNF FTSA //