Purification and characterization of bovine placental retinol-binding protein.
A major low mol wt acidic protein, 3B3, produced from cultures of day 29-90 bovine allantoic membranes (in the presence of [3H]leucine or [35S]methionine) and from day 29-60 allantoic fluid, has been purified. The protein consisted of three isoelectric variants (pI 5.3-6.1) of identical mol wt (23,200 +/- 900) when analyzed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Amino-terminal sequence analysis of 3B3 isolated from allantoic fluid on the first 43 amino acids showed that 3B3 had 93% and 91% homology with rabbit and human plasma retinol-binding protein (RBP), respectively. The UV absorption spectrum and the fluorescence excitation and emission spectra of purified 3B3 from both sources indicated the presence of bound retinol. Rabbit antiserum was raised against placental RBP (3B3) isolated from allantoic membrane culture medium. Placental RBP was immunoprecipitated from radiolabeled allantois and chorion culture medium and was detected in allantoic membrane culture medium and allantoic fluid by Western blotting. These results suggested that bovine placental membranes secrete RBP into allantoic fluid and that placental RBP may play important roles in vitamin A metabolism in the developing embryo.
Liu
K H
KH
Department of Animal Science, University of Tennessee, Knoxville 37901.
Baumbach
G A
GA
Gillevet
P M
PM
Godkin
J D
JD
D000482:Allantois / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007106:Immune Sera; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010920:Placenta / Q000378:metabolism*; D012177:Retinol-Binding Proteins / Q000302:isolation & purification* / Q000378:metabolism; D054839:Retinol-Binding Proteins, Plasma
D007106:Immune Sera; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma