Can you please specify what do you mean by saying "have not succeeded". There was no protein at all or you weren't able to detect a specific membrane-bound protein?

Hello Violetta, I have isolated cytosolic proteins, like different isoforms of metallothionein, but not membrane-bound proteins like zinc transporters. I'm currently studying certain proteins that interact with zinc and those that are associated with the membrane I have not being able to detect it using Western Blot.

Maria,

The Mem-PER™ Plus Membrane Protein Extraction Kit from Thermo Fisher utilizes CHAPS as a detergent in its membrane solubilizing mixture (verified in its SDS documentation). So, I guess, to isolate membrane-bound proteins, you can first lyse the cells using a mild detergent to solubilize cytosolic proteins, and then add a buffer based on CAPS to extract the membrane proteins effectively.