Abstract Background Evolution of splice sites is a well-known phenomenon that results in transcript diversity during human evolution.Many novel splice sites are derived from repetitive elements and may not contribute to protein products.Here, we analyzed annotated human protein-coding exons and identified human-specific splice sites that arose after the human-chimpanzee divergence.Results We analyzed multiple alignments of the annotated human protein-coding exons and their respective orthologous mammalian genome sequences to identify 85 novel splice sites (50 splice acceptors and 35 donors) in the human genome.
The novel protein-coding exons, which are expressed either constitutively or alternatively, WHEAT BRAN produce novel protein isoforms by insertion, deletion, or frameshift.We found three cases in which the human-specific isoform conferred novel molecular function in the human cells: the human-specific IMUP protein isoform induces apoptosis of the trophoblast and is implicated in pre-eclampsia; the intronization of a part of SMOX gene exon produces inactive spermine oxidase; the human-specific NUB1 isoform shows Vacuum Speed Control Cover reduced interaction with ubiquitin-like proteins, possibly affecting ubiquitin pathways.Conclusions Although the generation of novel protein isoforms does not equate to adaptive evolution, we propose that these cases are useful candidates for a molecular functional study to identify proteomic changes that might bring about novel phenotypes during human evolution.