Identification and expression of glycine decarboxylase (p120) as a duck hepatitis B virus pre-S envelope-binding protein.
A 120-kilodalton protein (p120) was identified in the duck liver that binds to several truncated versions of duck hepatitis B virus (DHBV) pre-S envelope protein, suggesting p120 may serve as a DHBV co-receptor. The amino acid sequences of tryptic peptides from purified p120 were found to be the duck p protein of the glycine decarboxylase complex (DGD). DGD cDNA cloning revealed extensive protein conservation with the chicken homologue except for several insertions in the N-terminal leader sequence. The DGD cDNA contained no in-frame AUG codon at the predicted initiation site of the open reading frame, and site-directed mutagenesis experiments established an AUU codon as the translational initiator. The DGD protein expressed in rabbit reticulocyte lysates bound truncated DHBV pre-S protein identical to that of p120 derived from duck liver confirming DGD as p120. Moreover, transfection studies in liver- and kidney-derived cells revealed both cell surface and cytoplasmic expression of the protein. Cloning of the glycine decarboxylase cDNA will permit a direct test of whether it functions as a cell surface co-receptor or as a co-factor in the DHBV replication cycles.
Li
J
J
Molecular Hepatology Laboratory, Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129, USA.
Tong
S
S
Wands
J R
JR
D000594:Amino Acid Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002645:Chickens; D003001:Cloning, Molecular; D003062:Codon; D004372:Ducks; D015723:Gene Library; D050959:Glycine Decarboxylase Complex; D050841:Glycine Dehydrogenase (Decarboxylating); D015611:Hepatitis B Virus, Duck / Q000378:metabolism*; D008099:Liver / Q000196:embryology* / Q000821:virology*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012156:Reticulocytes / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014759:Viral Envelope Proteins / Q000378:metabolism*
D003062:Codon; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; C077433:Pre-S protein, Duck hepatitis B virus; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; D000594:Amino Acid Oxidoreductases; D050959:Glycine Decarboxylase Complex; D050841:Glycine Dehydrogenase (Decarboxylating)