{APPRIS} is a system that deploys a range of computational methods to provide annotations of alternative splice isoforms and identify principal isoforms for vertebrate species. These annotations are based on the modules of the APPRIS Database.

The APPRIS principal isoform for each gene is selected as the principal isoform by combining protein structural information,functionally important residues and evidence from cross-species alignments.

The server has been used to annotate the Human genome as part of the GENCODE consortium but {APPRIS} also has annotations for other species. The main data source for {APPRIS} are the Ensembl annotations and sequences.