The location of potential alternative isoforms would also be affected for some isoforms. A total of 1287 genes would generate isoforms with differing numbers of cellular or mitochondrial signal sequences, and 2697 genes would generate isoforms with differing numbers of trans-membrane helices. In addition, 8842 genes contained at least one transcript that appeared to be subject to non-neutral evolution. We were able to select a constitutive variant for 16,553 protein-coding genes (80%) based on the output of the methods in APPRIS (Tress et al. 2008).
