ELISA is another immunological technique that you could use if you have an antibody. If the protein is an enzyme, you could use an assay for its catalytic activity. If it is a receptor, you could measure binding of a high-affinity ligand.

You can use flow cytometry and measure your surface expressed protein after transfecting cells with a plasmid that carries the gene of the protein.

Adam B Shapiro I do have an antibody but I'm not sure how ELISA works in my case. Could you please explain more? My protein is an ion channel.

Salim Al Hajri My cells are big for the flow cytometry. They are Xenopus oocyte.

Here is the Wikipedia articles about ELISA:

https://en.wikipedia.org/wiki/ELISA