title: Cloning, expression, and characterization of a novel guanylate-binding protein, GBP3 in murine erythroid progenitor cells.
abstract: We report the molecular cloning of a novel guanylate-binding protein (GBP), termed mouse GBP3 (mGBP3) in Friend virus-induced mouse erythroid progenitor (FVA) cells. The 71-kDa mGBP3 belongs to a family of known GBPs that contain the first two consensus motifs, GXXXXGK(S/T) and DXXG, but lack the third element, (N/T)KXD, found in typical GTP-binding proteins. Recombinant mGBP3 protein, expressed using a baculovirus expression system, binds to agarose-immobilized guanine nucleotides (GTP, GDP and GMP). Moreover, mGBP3 has been found to have an intrinsic GTPase activity with K(m) and Vmax values of 77 +/- 4 microM and 21 +/- 0.5 pmol min-1 microgram-1 of protein, respectively. The mGBP3 is distinct from the other GBPs, in that it does not have an isoprenylation/methylation motif CAAX at the carboxyl terminus. The mGBP3 appears to be localized in the cytosol based on immunofluorescence staining. Although the mGBP3 transcript is expressed to a varying degree in numerous mouse tissues, the message is most abundant in FVA cells. The mGBP3 transcript increases in FVA cells undergoing differentiation to a maximum within a few hours and then decreases to an undetectable level by 24 h. These results, taken together, suggest that mGBP3 is a novel member of a family of guanylate-binding proteins, which plays a role in the erythroid differentiation. The nucleotide sequence reported in this paper has been submitted to the GenBank with accession number U44731.
authors.affiliation: Department of Pharmacology, University of Missouri-Columbia, School of Medicine 65212, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Han
authors.forename: D J
authors.initials: DJ
authors.lastname: Park
authors.forename: R W
authors.initials: RW
authors.lastname: Lim
authors.forename: J H
authors.initials: JH
authors.lastname: Im
authors.forename: H D
authors.initials: HD
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D015672:Erythroid Precursor Cells / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins; D006150:Guanine Nucleotides / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions
chemical_list: D002352:Carrier Proteins; C485134:Gbp3 protein, mouse; D006150:Guanine Nucleotides; D012333:RNA, Messenger; D019204:GTP-Binding Proteins