The family of hepatoma-derived growth factor proteins: characterization of a new member HRP-4 and classification of its subfamilies.
Hepatoma-derived growth factor (HDGF)-related proteins (HRPs) comprise a family of polypeptides named after HDGF, which was identified by its mitogenic activity towards fibroblasts. In the present study, we describe a hitherto unknown HRP, termed HRP-4. The cDNA of bovine HRP-4 (bHRP-4) predicts a polypeptide of 235 amino acids. Northern- and Western-blot analyses of various bovine tissues demonstrated that HRP-4 is only expressed in the testis. Recombinantly produced bHRP-4 and murine HDGF (mHDGF) histidine-tagged polypeptides display growth-factor activity for cultured primary human fibroblasts at an optimum concentration of 1 ng/ml in serum-free medium. The growth-factor activity declines with increasing concentrations to reach background levels at 1 microg/ml. The expression of the fusion proteins, bHRP-4-green fluorescent protein and mHDGF-green fluorescent protein, in HEK-293 cells demonstrates nuclear localization of the proteins. bHRP-4 and mHDGF bind to the glycosaminoglycans heparin and heparan sulphate, but not to chondroitin sulphate. Affinity constants determined for these interactions are between 6 and 42 nM. Comparison of the bHRP-4 amino acid sequence with HRP-1-3 and p52/75/lens epithelium-derived growth factor (LEDGF) shows that these proteins share a conserved N-terminal part of 91 amino acids but have C-termini of different lengths and charge. This demonstrates the modular structure of these proteins and allows its classification into three groups based on charge, size and sequence comparison. HRP-4, HRP-1 and HDGF are small acidic proteins, HRP-3 is a small basic protein, and HRP-2 and p52/75/LEDGF are larger basic proteins.
Dietz
Frank
F
Institut für Physiologische Chemie, Rheinische Friedrich-Wilhelms Universität, Nussallee 11, 53115 Bonn, Germany.
Franken
Sebastian
S
Yoshida
Kenya
K
Nakamura
Hideji
H
Kappler
Joachim
J
Gieselmann
Volkmar
V
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002455:Cell Division / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000737:chemistry; D005347:Fibroblasts; D015723:Gene Library; D006025:Glycosaminoglycans / Q000378:metabolism; D006133:Growth Substances / Q000737:chemistry* / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D013737:Testis / Q000378:metabolism; D014162:Transfection
D018076:DNA, Complementary; D006025:Glycosaminoglycans; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; C051610:hepatoma-derived growth factor