The object of the present invention is a procedure for the distribution, separation and purification in aqueous solution of recombinant proteins, based on the utilization of polypeptides with choline affinity. The invention is based on a phenomenon consisting of that two aqueous solutions with determinated components can be mixed, being distributed finally in two phases with different density. The fusionated proteins to said polypeptides with choline affinity are preferably located in one of the phases, while most of the cell extract proteins tend to go to the opposite phase. After a series of washings for removing the rest of the not desired material, this location can be inverted through the addition of a soluble molecule with affinity by the polypeptide fusionated to the protein of interest. This procedure allows modulating at convenience the presence of the protein or polypeptide of interest in one phase or another, possibiliting its purification with a high yield and purity grade. The invention represents an economic and scalable way of recombinant protein separation labelled preferably with choline-binding domains.
