Splicing Sequence signal

To make mRNA, the primary transcript must be spliced to bring the protein-coding sequences (exons) together and to remove the intervening sequences (introns). The splice signals consist of a 5 and a 3 set of sequences that are always found at splice junctions. However, this is generally believed to provide too little information to recognize a splice site specifically and correctly. Some sequences in the intron are also important. 

FcyRIIB generates three transcripts from alternative splicing of exons encoding either the cytoplasmic region (transcripts bl, b2) or the signal sequence (b3). 

The signal sequences that determine the location of splicing are shown in Fig. 1.47. Decisive are sequences at the border between exon and intron, foimd as conserved sequences at the 5 (donor site) and 3 (acceptor site) of the splice site. The intron is removed in the form of a lasso. Donor and acceptor sites are then precisely joined together. 

Fig. 1.47. Signal sequences for splicing. A splice site is determined by sequences on the 5 side of an intron (5 splice site) and on the 3 side of an intron (3 sphce site).

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