Carboxyl terminal analysis of human B-48 protein confirms the novel mechanism proposed for chain termination.
In this study we have confirmed the presence of a single base difference between intestinal mRNA coding for B-48 and hepatic mRNA coding for B-100, which results in the substitution of a stop codon (UAA) for a glutamine codon (CAA) at a point corresponding to amino acid residue 2153 in the B-100 sequence. Based on this finding, B-48 is predicted to terminate at residue 2152 with the sequence ... Met Ile. To confirm this finding at the protein level, B-48 and B-100 were each digested with cyanogen bromide and the digestion products were analysed for the presence of isoleucine. Isoleucine was found only in cyanogen bromide digests of B-48 confirming that only B-48 terminates with the predicted amino acid sequence ... Met Ile.
Hardman
D A
DA
Cardiovascular Research Institute, University of California, San Francisco 94143-0130.
Protter
A A
AA
Schilling
J W
JW
Kane
J P
JP
D000595:Amino Acid Sequence; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D003062:Codon; D006801:Humans; D007422:Intestines / Q000032:analysis; D008099:Liver / Q000032:analysis; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational; D012333:RNA, Messenger / Q000032:analysis; D013728:Terminator Regions, Genetic
D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D003062:Codon; D012333:RNA, Messenger