Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019163 (hepatitis B)
 38,309 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatitis B virus precore and core proteins are related. The precore protein contains the entire sequence of the core protein plus an amino-terminal extension of 29 amino acids. The amino-terminal extension of the precore protein contains a signal sequence for the secretion of the precore protein. This signal sequence is removed after the translocation of the precore protein across the endoplasmic reticulum membrane to produce the precore protein derivative named P22. We demonstrate that both P22 and the core protein can be phosphorylated in cells. Microsomal fractionation and trypsin digestion experiments demonstrate that a fraction of phosphorylated P22 is located in the endoplasmic reticulum lumen. Phosphorylation of P22 likely occurs in the carboxy terminus, since the P22 derivative P16, which lacks the carboxy terminus of P22, is not phosphorylated. Linking the carboxy terminus of the precore-core protein to heterologous secretory and cytosolic proteins led to the phosphorylation of the resulting chimeric proteins. These results indicate that phosphorylation of P22 and the core protein is likely mediated by cellular kinases.
 ...
PMID:Phosphorylation of hepatitis B virus precore and core proteins. 185 14

At least two proteolytic events are involved in the biogenesis of hepatitis B virus e antigen. The first proteolytic event removes the signal peptide and results in the translocation of the precursor protein, P22, into the lumen of the endoplasmic reticulum (ER). The second proteolytic event removes the carboxy-terminal arginine-rich sequence of P22 and converts it to the 16-kDa hepatitis B virus e antigen end product. In contrast to the first proteolytic event, the second proteolytic event is suppressed by brefeldin A, a chemical that inhibits the transport of protein from the ER to the Golgi apparatus. In subcellular fractionation experiments, P22 was detected in both the ER and the Golgi fractions, but P16 was detected only in the Golgi fraction. On the basis of these results, we conclude that the conversion of P22 to P16 occurs ina post-ER compartment, mostly likely the Golgi apparatus.
 ...
PMID:Proteolytic conversion of hepatitis B virus e antigen precursor to end product occurs in a postendoplasmic reticulum compartment. 187 Feb 12

To map the location of hepatitis B core and e Ag (HBcAg and HBeAg) on the hepatitis B virus core particle, we produced and analyzed four synthetic peptides which correspond to the most hydrophilic regions of the core P22 protein. Each peptide was tested in an ELISA for the ability to inhibit the binding between rHBcAg or rHBeAg and either polyclonal or monoclonal anti-HBc or anti-HBe antibodies. The former comprised 20 antisera positive for anti-HBc (anti-HBs and anti-HBe negative) and five antisera positive for anti-HBe and anti-HBc; the latter included three anti-HBc mAb developed in independent laboratories: G6F5, C51B10, and F8, as well as two anti-HBe mAb, E2 and E6. These experiments revealed the presence of a major HBcAg epitope expressed on C3, a peptide which covers amino acids 107-118 and reacted with all polyclonal and monoclonal antibodies tested. Another peptide, C2, sequence 73-85, reacted with 26% of human antisera but none of the anti-HBc mAb. None of the peptides seemed to express HBeAg activity because they do not cause any significant inhibition of the HBeAg/anti-HBe reaction. These data indicate the expression of an immunodominant HBcAg determinant on a linear dodecapeptide and argue against a strict conformation dependency of this Ag.
 ...
PMID:Identification of a major hepatitis B core antigen (HBcAg) determinant by using synthetic peptides and monoclonal antibodies. 246 91

Highly purified hepatitis B virus core particles were obtained in large amounts from the cytoplasm of infected human liver cells. This DNA polymerase-negative core preparation had only hepatitis B core antigen-specific antigenicity and showed a surprising stability. Two forms of a single protein of 22,000 molecular weight, P22, were resolved electrophoretically; the slower moving species, P22a, appeared to be a reduced form of the protein, and the faster moving species, P22b, could have represented a conformational isomer containing an intramolecular disulfide bond(s). The immunological properties and DNA-binding activity of the reduced form, P22a, were examined following separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by transfer onto nitrocellulose membranes (Western blotting). We found that the hepatitis B virus C gene protein shared the antigenic site responsible for both hepatitis B core and e antigen reactivity. We also demonstrated that the core protein(s) bound specifically the genomic hepatitis B virus DNA in comparison with a plasmid DNA (pBR322). This last observation was further substantiated by a radioimmunological method. P22a was also found to be phosphorylated in vitro by the endogenous protein kinase activity, copurified with the hepatitis B core antigen particles. These findings suggest that P22 is a multifunctional protein which is incorporated into core particles within the cytoplasm of the host cell before DNA encapsidation. A critical role of this protein in hepatitis B virus assembly is suggested.
 ...
PMID:HBc and HBe antigenicity and DNA-binding activity of major core protein P22 in hepatitis B virus core particles isolated from the cytoplasm of human liver cells. 257 75

The precore and core proteins of hepatitis B virus have identical deduced amino acid sequences other than a 29-residue amino-terminal extension (precore region) on the precore protein. The first 19 of these residues serve as a signal sequence to direct the precore protein to the endoplasmic reticulum, where they are cleaved off with formation of precore protein derivative P22 for secretion. In this report, we show that P22 can alternatively be transported into the nucleus following signal peptide cleavage. Experiments with deletion mutants indicated that this nuclear transport proceeds via the cytosol and is dependent on the amino-terminal portion of P22. Thus, the hepatitis B virus precore protein is a secreted, cytosolic, and nuclear protein.
 ...
PMID:Transport of hepatitis B virus precore protein into the nucleus after cleavage of its signal peptide. 258 3

Large hepatitis B surface antigen polypeptides with apparent molecular sizes of 39,000 and 43,000 daltons (P39 and P43) were liberated from a purified preparation of Dane particles of subtype adr. They were tested for reactivity with monoclonal antibodies raised against three synthetic oligopeptides representing fundamental sequences of the pre-S region in deoxyribonucleic acid of hepatitis B virus (subtype adr), as well as with monoclonal antibody against the major surface antigen polypeptide (P22) coded for by the S gene. Both P39 and its glycosylated form P43 bound to all four monoclonal antibodies, thereby indicating that they were coded for by the sequence of 1200 nucleotides, from the second ATG codon in the pre-S region to the stop codon of the S gene. Both P39 and P43 bound to polymerized human and chimpanzee albumins, but not to polymerized albumin from species without susceptibility to hepatitis B virus. Due to their presence in Dane particles and the expression of a polyalbumin receptor, the immune responses against P39 and P43 may have significance in infection with hepatitis B virus and its immunoprophylaxis.
 ...
PMID:Large hepatitis B surface antigen polypeptides of Dane particles with the receptor for polymerized human serum albumin. 300 98

Using synthetic hepatitis B virus (HBV) mRNAs, we have shown that expression of HBV core-antigen gene sequences in Xenopus oocytes leads to the stable accumulation of 21-kDa cytoplasmic core protein (P21). In contrast, expression of precore plus core sequences leads mainly to the secretion of a heterogeneous population of proteins ranging in size from 15 to 22 kDa that collectively display viral e antigen (HBeAg) activity. We demonstrate that the precore region contains a cleavable 19 amino acid signal peptide that targets the precore proteins to the secretory pathway. The initial product of translocation (P22) is further processed during migration through the secretory pathway, apparently by a series of cleavage events at the arginine-rich carboxyl terminus, to yield multiple proteins of 15-18 kDa (P15-P18) that are secreted along with some P22. Our results indicate that serum HBeAg is generated by a signal peptide-mediated secretion event dependent on precore sequences.
 ...
PMID:A signal peptide encoded within the precore region of hepatitis B virus directs the secretion of a heterogeneous population of e antigens in Xenopus oocytes. 318 31

Four major polypeptides with mol. wt. of 22000, 25000, 52000 and 68000 were isolated from solubilized preparations of hepatitis type B surface antigen (HBsAg). These four populations, referred to as P22, P25, P52 and P68, respectively, were used to immunize guinea-pigs. Guinea-pigs were also inoculated with HBsAg and with purified human serum albumin (HuSA). These antisera were utilized to establish that intact HBsAg particles are associated with HuSA antigenic reactivity. HuSA antigenic determinants were associated with purified preparations of P68. HuSA antigenic activity was not detected with purified preparations of P22, P25 and P52 or with respective specific antisera to each of the above. However, purified P68 contained the antigenic determinants of both host protein and hepatitis B virus-specified protein origin.
 ...
PMID:Antigenic relationship of a hepatitis B surface antigen-derived polypeptide and human serum albumin. 615 94

Hepatitis B virus, and hepatitis B surface antigen particles co-occurring with hepatitis B e antigen, have the receptor for polymerized human and chimpanzee albumins that may be involved in the hepatotropism of hepatitis B virus. We identified the receptor on a hepatitis B surface antigen polypeptide with a molecular size of 31,000 daltons (P31). P31 bound to polymerized albumins from human and chimpanzee, but did not react with polymerized albumins from the experimental animals without susceptibility to hepatitis B virus. P31 was composed of the major polypeptide of hepatitis B surface antigen with a molecular size of approximately 22,000 daltons (P22) and additional 55 amino acid residues coded by the pre-S region in the hepatitis B virus-specific deoxyribonucleic acid. Because P22 did not react with polymerized albumin, the sequence of 55 amino acid residues in the pre-S region appeared to bear the receptor. Polypeptides with the receptor for polymerized albumin may make an efficacious hepatitis B vaccine, because they could raise antibodies against the putative site on hepatitis B virus capable of binding with hepatocytes to initiate the infection.
 ...
PMID:A hepatitis B surface antigen polypeptide (P31) with the receptor for polymerized human as well as chimpanzee albumins. 630 55

The receptor for polymerized human and chimpanzee albumins has been identified on a hepatitis B surface antigen polypeptide of approximately 31,000 daltons. The polypeptide, designated P31, is composed of the major polypeptide of hepatitis B surface antigen (P22) and an additional, as yet unidentified, amino acid sequence. We split P31 with cyanogen bromide and obtained a polypeptide of approximately 8000 daltons (P8) that contained carbohydrate. P8 could bind to polymerized human and chimpanzee albumins, but not to polymerized albumins from animals without susceptibility to hepatitis B virus. The amino acid composition of P8 closely resembled that of 55 amino-acid sequence coded by the pre-S region in the deoxyribonucleic acid of hepatitis B virus. Using monoclonal antibody against P8, a solid-phase sandwich radioimmunoassay was developed for the specific determination of hepatitis B surface antigen bearing the receptor for polymerized albumin in the serum of patients with hepatitis B virus infection.
 ...
PMID:A polypeptide containing 55 amino acid residues coded by the pre-S region of hepatitis B virus deoxyribonucleic acid bears the receptor for polymerized human as well as chimpanzee albumins. 632 44


1 2 3 Next >>