Ribbon representation showing the MAp17 and the N-terminal CAp24 domain of the unprocessed Pr55Gag. Ribbon diagram of the MAp17  and CAp24  depicting the structural rearrangemts that takes place in the N-terminal domain (NTD) of CAp24 upon proteolytic processing at the MAp17-CAp24 junction (indicated with a sax). The model to the right represents a processed NTD CAp24 showing the β-hairpin formation which is stabilized by the salt-bridge formation between the imino terminal Pro 1 and Asp 51. For clarity, Por 1 and Asp 51 are shown as filled circles. The ribbon diagrams were generated with the PyMOL  and modified with Adobe Photoshop software.