Characterization of bovine angiogenin-1 and lactogenin-like protein as glycyrrhizin-binding proteins and their in vitro phosphorylation by C-kinase.
Angiogenin-1 (p15, an angiogenesis inducer with RNase activity) and lactogenin-like protein (p17) isolated from partially purified bovine lactoferrin (bLF) preparations were characterized as glycyrrhizin (GL)-binding proteins (gbPs). As expected, bLF-affinity column chromatography confirmed these two gbPs to be bLF-binding proteins. These two purified gbPs exhibited RNase activities when incubated with poly(C) as a substrate. Both GL and glycyrrhetinic acid (GA) at 100 microM significantly inhibited RNase activities of these two gbPs, both of which functioned as phosphate acceptors of C-kinase in vitro. Phosphorylation of p15 and p17 by C-kinase was inhibited by GA in a dose-dependent manner with the 50% inhibition dose (ID50) of approx. 10 microM, whereas GL required a relatively high dose (300 microM) to inhibit significantly it. A GA derivative (oGA, ID50=approx. 0.3 microM) was found to be a potent inhibitor of the C-kinase-mediated phosphorylation of these two gbPs in vitro. In addition, a possible physiological significance of C-kinase on the physiological interaction between bLF and two bLF-binding proteins (p15 and p17) is noted.
Tanigawa
K
K
Laboratory of Clinical Chemistry, School of Allied Health Sciences, Kitasato University, Sagamihara, Japan.
Fujihara
M
M
Sakamoto
R
R
Yanahira
S
S
Ohtsuki
K
K
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D006034:Glycyrrhetinic Acid / Q000494:pharmacology; D019695:Glycyrrhizic Acid / Q000494:pharmacology; D008894:Milk Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D012259:Ribonuclease, Pancreatic / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism
D002352:Carrier Proteins; D008894:Milk Proteins; C086010:glycyrrhizin-binding proteins; C121812:lactogenin; D019695:Glycyrrhizic Acid; D011493:Protein Kinase C; D012260:Ribonucleases; C046366:angiogenin; D012259:Ribonuclease, Pancreatic; D006034:Glycyrrhetinic Acid