The MBP （Maltose Binding Protein） tag is a widely used fusion tag that enhances the solubility of many recombinant proteins. It is a 42 kDa protein derived from _E. coli_ and is employed to improve the expression and purification of target proteins. The MBP tag allows for one-step purification using amylose resin, where the fusion protein binds to the resin and can be eluted with maltose. This tag is particularly useful for increasing the solubility and stability of difficult-to-express proteins and can be cleaved from the target protein using specific proteases, leaving the protein of interest pure and tag-free. The MBP tag's mechanism for enhancing solubility is not fully understood but is believed to involve stabilizing the target protein and protecting it from degradation during and after synthesis. It is also proposed to act as a chaperone, helping the target protein fold correctly. The use of MBP tag can lead to higher cytoplasmic yields due to efficient translation initiation and is a reliable tool for recombinant protein production campaigns.