Apolipoprotein B-48 is the product of a messenger RNA with an organ-specific in-frame stop codon.
The primary structure of human apolipoprotein (apo) B-48 has been deduced and shown by a combination of DNA excess hybridization, sequencing of tryptic peptides, cloned complementary DNAs, and intestinal messenger RNAs (mRNAs) to be the product of an intestinal mRNA with an in-frame UAA stop codon resulting from a C to U change in the codon CAA encoding Gln2153 in apoB-100 mRNA. The carboxyl-terminal Ile2152 of apoB-48 purified from chylous ascites fluid has apparently been cleaved from the initial translation product, leaving Met2151 as the new carboxyl-terminus. These data indicate that approximately 85% of the intestinal mRNAs terminate within approximately 0.1 to 1.0 kilobase downstream from the stop codon. The other approximately 15% have lengths similar to hepatic apoB-100 mRNA even though they have the same in-frame stop codon. The organ-specific introduction of a stop codon to a mRNA appears unprecedented and might have implications for cryptic polyadenylation signal recognition and RNA processing.
Chen
S H
SH
Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
Habib
G
G
Yang
C Y
CY
Gu
Z W
ZW
Lee
B R
BR
Weng
S A
SA
Silberman
S R
SR
Cai
S J
SJ
Deslypere
J P
JP
Rosseneu
M
M
D000595:Amino Acid Sequence; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002915:Chylous Ascites / Q000378:metabolism; D003062:Codon; D004247:DNA / Q000235:genetics; D006801:Humans; D007421:Intestine, Small / Q000032:analysis; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010446:Peptide Fragments; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D014357:Trypsin / Q000378:metabolism
D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D003062:Codon; D010446:Peptide Fragments; D012333:RNA, Messenger; D004247:DNA; D014357:Trypsin