A SEQUENCE COMPILATION AND COMPARISON OF EXONS THAT ARE ALTERNATIVELYSPLICED IN NEURONS

Alternative splicing is an important regulatory mechanism to create pr otein diversity. Tn order to elucidate possible regulatory elements co mmon to neuron specific exons, we created and statistically analysed a database of exons that are alternatively spliced in neurons. The spli ce site comparison of alternatively and constitutively spliced exons r eveals that some, but not all alternatively spliced exons have splice sites deviating from the consensus sequence, implying diverse patterns of regulation. The deviation from the consensus is most evident at th e -3 position of the 3' splice site and the +4 and -3 position of the 5' splice site. The nucleotide composition of alternatively and consti tutively spliced exons is different, with alternatively spliced exons being more AU rich. We performed overlapping k-tuple analysis to ident ify common motifs. We found that alternatively and constitutively spli ced exons differ in the frequency of several trinucleotides that canno t be explained by the amino acid composition and may be important for splicing regulation.