Methods needed for gene/protein identification and function - (Nov/15/2007 )

Hello, I'm writing a 'mach' grant proposal for one of my advanced bio courses. I answering some answered question from a journal that was written about 2 co-expressed genes in D. melanogaster that are used for CO2-sensitivity. However, the article did not specify as to the individual physiological roles of each gene in CO2 recognition. They did mention that their previous attempts to tag these two proteins while retaining function have failed, but didn't mention which tagging methods they used. However, possible roles proposed include one subunit acting as a chaperon co-receptor while the other acts to differentiate between ligands, or possibly both subunits are required for both functions.

Therefore, I need some possible methods of gene tagging to determine the roles of these two gene, while retaining their function.
Genes: Gr21a and Gr63a

I did find a method called 'split green' to tag proteins, but I need some more. ANY help will be appreciated. Thank you.

commonly one would use an epitope tag, small sequences at either the N or C terminus (varies for each protein). Usually they do not interfere with function, but one never knows. You have got to tag on both ends and compare them.

Tagging using fluorescent proteins is not really advisable for functional studies.

Thank you for your reply.

Anyone have anything else to add?