I am looking for studies on how many protein isoforms have different functions, preferably in human. We know that a great many, if not most, of human genes are alternatively spliced and that many produce different protein isoforms. Has anyone looked at how many of these isoforms have different cellular functions? If someone could point me to a published paper, that would be great.
If no such study has been made, can anyone recommend a database from which this information could be extracted? GeneOntology is gene based so the information cannot be found there. Genes will be annotated to specific terms, not their protein isoforms. Also, I would need to be able to do this in a high throughput manner, I am not interested in specific proteins but in what percentage of all isoforms have different functions.
Ideally, I would like to be able to extract, for every human gene, the list of the different protein isoforms it encodes and whether their functions differ, or at least what those functions are.
This is an interesting endeavor. One of the first things to be considered, in my opinion, is the definition of function, or how nuanced you need to be to properly, completely describe that protein's function. Most isoforms will likely have the same basic function but differ in something like sub-cellular localization or loss of a regulatory sub-domain. In other words, alternate splicing will lead to different protein isoforms with slightly different function in light of the primary function of the protein.
Yup, exactly, that's what I want to analyze. My first step though is to see how often different isoforms are annotated to different functions and I can't figure out where to get that information because too many of the high-troughput functional assays are gene based.