Exon-skipping is responsible for the 9 amino acid residue deletion occurring near the N-terminal of human beta-casein.
Interspecies comparison and alignment of the beta-casein N-terminal sequence, taking into account its exon modular splitting derived from the known structural organization of the relevant genes, has revealed that a 9 amino acid residue sequence, corresponding to that encoded by the third exon of the other species genes, is lacking in human beta-casein. Using the polymerase chain reaction technique, we have amplified a human genomic 1-kb fragment, spanning from exon 2 to exon 4, which was subsequently cloned and sequenced. One hundred base pairs (bp) upstream from exon 4 and 737 bp downstream of exon 2, a 27-bp virtual exon 3 sequence, probably skipped during the course of pre-mRNA splicing, was identified. We discuss the possibility that this out-splicing event might be due to the weak strength of the 3' acceptor site and/or to the secondary structure sequestering of the branch site sequence.
Martin
P
P
Laboratoire de Génétique biochimique, Institut National de la Recherche Agronomique, CRJ, Jouy-en-Josas, France.
Leroux
C
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D002364:Caseins / Q000235:genetics*; D003001:Cloning, Molecular; D005091:Exons / Q000235:genetics*; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D012322:RNA Precursors; D012326:RNA Splicing; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D002364:Caseins; D012322:RNA Precursors