Mycobacterial porin

MspA porin is a membrane porin produced by Mycobacteria, allowing hydrophilic nutrients to enter the bacterium. The protein forms a tightly interconnected octamer with eightfold rotation symmetry that resembles a goblet and contains a central channel. Each protein subunit contains a beta-sandwich of immunnoglobulin-like topology and a beta-ribbon arm that forms an oligomeric transmembrane beta-barrel.