Process for producing a membrane protein

A pilot or industrial scale process for producing a membrane protein comprising the steps of:

• a. expressing said membrane protein in a host organism present in an aqueous medium,
• b. i) liberating the membrane protein from the host organism by mechanically lysing cells of the host organism to form lysed cell membrane fragments that include the membrane protein and ii) isolating the lysed cell membrane fragments including the membrane protein in the form of a pellet by a first centrifugation,
• c. adding a detergent solution to a resuspension of the pellet obtained in b to solubilize the membrane protein to form a solubilized membrane protein,
• d. recovering a liquid fraction of the solubilized membrane protein obtained in c as a supernatant by a second centrifugation,
• e. subjecting the liquid fraction to chromatography to bind or retain the solubilized membrane protein on a stationary phase, and
• f. eluting the protein from the stationary phase to produce the solubilized membrane protein, wherein the first and second centrifugations in steps b and d are each performed at 500 g to 30,000 g and the process does not include ultracentrifugation of the liquid fraction obtained in steps b and d.