I just tried to send this mail to the list but it seems as if it didn't go through - I will make another try. ______________________________________________________________________ ___ Dear list, This might be a question that has been discussed previously but I could not find any good solution for it. I have lists of human proteins from various proteomics studies that I want to compare with regards to the GO terms associated to them. I have the RefSeq GI protein id for the proteins and my questions is how I best map those to other identifiers that I can use in subsequent GO analysis? It might be that this problem is solved best outside R but maybe someone can give me a hint to a solution. For me this is a problem that comes up quite often - the need to map between different identifiers - and I have not yet found any really good solution to it. If I for example use IPI (International Protien Index) I always loose some proteins/genes since the coverage is rather bad, but maybe there is no solution that will give perfect mapping?! Any input will be greatly appreciated! Thank you! Best regards, Lina Hultin-Rosenberg Karolinska Biomics Center Karolinska Institute