Structural 3D visualization of gp20 protein. Gp20 is a portal protein of the bacteriophage T4 and is part of the machine that introduces DNA (deoxyribonucleic acid) into the capsid. This lateral view ribbon model was visualized with ChimeraX software. Secondary structures are colour-coded: red for helices, yellow for strands and green for loops T4 is a bacteriophage that infects Escherichia coli bacteria. Phages such as T4 are a possible therapy against multi-drug-resistant bacteria.