Expression of apolipoprotein B mRNAs encoding higher- and lower-molecular weight isoproteins in rat liver and intestine.

Two B apolipoproteins (apo) are present in human plasma, designated apoB-100 and apoB-48, and represent translational products from mature apoB mRNAs that differ by a single base. Either the glutamine codon encoded by the single-copy apoB gene at nucleotide 6666 is transcribed and translated to produce apoB-100 or an RNA-editing mechanism substitutes a uracil for cytosine, altering this glutamine codon (CAA) to a stop codon (UAA), prematurely terminating translation to produce apoB-48. In the present report, editing of rat apoB transcripts was evaluated by amplification of RNA with the polymerase chain reaction by use of primers based on the apoB cDNA cloned from a rat liver cDNA library.

Tissue-specific expression of apolipoprotein A-I (ApoA-I) is regulated by the 5'-flanking region of the human ApoA-I gene.

We have isolated and characterized a 2.5-kilobase pairs genomic DNA fragment which includes the 5'-flanking region and the first and second exons of the human apolipoprotein (apo) A-I gene. The major transcriptional start site was determined by primer extension analysis and is 235 base pairs (bp) upstream from the AUG translational start codon in liver and 234 bp upstream in the intestine.

Isolation and partial characterization of melanoma-associated antigens identified by autologous antibody.

The study of the autologous immune response to cancer avoids the difficulties encountered in the use of xenoantisera and may identify antigens of physiological relevance. However, the low titer and incidence of autologous antibody to melanoma have hampered further evaluation. By utilizing acid dissociation and ultrafiltration of serum, we have been able to augment the detectable autologous immune response to melanoma in the majority of patients studied.

Human apolipoprotein B (apoB) mRNA: identification of two distinct apoB mRNAs, an mRNA with the apoB-100 sequence and an apoB mRNA containing a premature in-frame translational stop codon, in both liver and intestine.

Human apolipoprotein B (apoB) is present in plasma as two separate isoproteins, designated apoB-100 (512 kDa) and apoB-48 (250 kDa). ApoB is encoded by a single gene on chromosome 2, and a single nuclear mRNA is edited and processed into two separate apoB mRNAs. A 14.

Identification of a novel in-frame translational stop codon in human intestine apoB mRNA.

Human apolipoprotein (apo) B exists in plasma as two isoproteins designated apoB-100 and apoB-48. ApoB-100 (512 kDa) and apoB-48 (250 kDa) are synthesized by the liver and intestine respectively. Analysis of apoB cDNA clones isolated from a human intestinal cDNA library revealed that the intestinal apoB mRNA contains a new in-frame translational stop codon.

Modulation of 1,25-dihydroxyvitamin D3 receptor by phospholipids and fatty acids.

The structural relationship between several lipids and their respective capacities to inhibit the specific binding of [3H]-1,25 (OH)2 vitamin D3 to chick intestinal cytosol preparations was investigated. The lipids investigated were: synthetic 3-sn-phosphatidylcholine and 3-sn-phosphatidic acid, egg yolk 3-sn-phosphatidylcholine and its corresponding phosphatidic acid, and free unsaturated fatty acids and their esters. The results indicate that at least three structural elements in the phospholipid molecule appear to be important; these are: 1) the structure of the fatty acid, 2) the anionic properties of the phospholipid phosphate group, and 3) the glycerol phosphate portion of the molecule.