A catalog of splice junction sequences was compiled by Stephen M. Mount, from nuclear and viral genes encoding proteins. The consensus sequence for donor sites was found to be CAG/GT AGT, and for acceptor sites, C N T CAG/G. These sequences were derived from 139 donor and 130 acceptor junctions. The GT-AG rule was consistently observed in these sequences, with the GT at the beginning of introns and AG at the end. However, some exceptions were noted, particularly in immunoglobulin genes. The study also showed that the AG dinucleotide does not appear in the -15 to -5 region of acceptor sites. The analysis of repeat lengths between donor and acceptor sequences revealed that the observed frequencies generally matched expected frequencies. The consensus sequences suggest that splice junctions are highly conserved, indicating a functional role in splicing. The study also discusses the possibility of a scanning mechanism for splicing at acceptor sites, where a component of the splicing machinery binds to a pyrimidine-rich region and moves until an AG is found. The results support the idea that splice junction sequences are essential for splicing and that the GT-AG rule is a key feature of these sequences. The study highlights the importance of these sequences in the splicing process and their conservation across different species.A catalog of splice junction sequences was compiled by Stephen M. Mount, from nuclear and viral genes encoding proteins. The consensus sequence for donor sites was found to be CAG/GT AGT, and for acceptor sites, C N T CAG/G. These sequences were derived from 139 donor and 130 acceptor junctions. The GT-AG rule was consistently observed in these sequences, with the GT at the beginning of introns and AG at the end. However, some exceptions were noted, particularly in immunoglobulin genes. The study also showed that the AG dinucleotide does not appear in the -15 to -5 region of acceptor sites. The analysis of repeat lengths between donor and acceptor sequences revealed that the observed frequencies generally matched expected frequencies. The consensus sequences suggest that splice junctions are highly conserved, indicating a functional role in splicing. The study also discusses the possibility of a scanning mechanism for splicing at acceptor sites, where a component of the splicing machinery binds to a pyrimidine-rich region and moves until an AG is found. The results support the idea that splice junction sequences are essential for splicing and that the GT-AG rule is a key feature of these sequences. The study highlights the importance of these sequences in the splicing process and their conservation across different species.