Rat cellular retinol-binding protein II: use of a cloned cDNA to define its primary structure, tissue-specific expression, and developmental regulation.
The primary structure of rat cellular retinol-binding protein (CRBP) II has been determined from a cloned cDNA. Alignment of this 134-amino acid, 15,580-Da polypeptide with rat CRBP revealed that 75 of 133 comparable residues are identical. Both proteins contain four tryptophan residues, which occupy identical relative positions in the two primary structures, providing a structural explanation for their similar fluorescence spectra when complexed to retinol. Two of the three cysteines in each single-chain protein are comparably positioned. Both polypeptides contain reactive thiol groups, but the rate of disruption of CRBP II-retinol complexes by p-chloromercuribenzoate is greater than that of CRBP-retinol. The small intestine contains the highest concentrations of CRBP II mRNA in adult rats. CRBP II mRNA is first detectable in intestinal RNA during the 19th day of gestation, a time that corresponds to the appearance of an absorptive columnar epithelium. Unlike in intestine, a dramatic fall in liver CRBP II mRNA concentration occurs immediately after birth. The CRBP II gene remains quiescent in the liver during subsequent postnatal development. These data suggest that ligand-protein interactions may be somewhat different for the two rat CRBPs. They also support the concept that CRBP II plays a role in the intestinal absorption or esterification of retinol and suggest that changes in hepatic metabolism of vitamin A occur during development.
Li
E
E
Demmer
L A
LA
Sweetser
D A
DA
Ong
D E
DE
Gordon
J I
JI
D000375:Aging; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D005333:Fetus; D005796:Genes; D007421:Intestine, Small / Q000254:growth & development; D008099:Liver / Q000254:growth & development; D008297:Male; D009693:Nucleic Acid Hybridization; D011247:Pregnancy; D014176:Protein Biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D012177:Retinol-Binding Proteins / Q000235:genetics*; D054840:Retinol-Binding Proteins, Cellular; D014158:Transcription, Genetic
D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular; D004247:DNA