Storage proteins of legumes are one of the main components of the human and animal diet. The substances collected in their seeds have the pro-health values, supporting the prevention of many civilization diseases. However, there are still many uncertainties about the mechanisms leading to the production of nutritious seeds. It is also difficult to identify which of their constituents and in what final form are responsible for the observed protective effects in vivo. In this work, on the background of different types of storage proteins, these deposited mainly in legumes were in the focus of interest. They were characterized on the example of pea (Pisum sativum) proteins. Mechanisms associated with their biosynthesis and transport to specific cellular compartments was presented. Ways of their post-translational processing, segregation and storage in the specific vacuoles were also discussed. Therefore, the paper presents the state-of-the-art knowledge concerning the processes making the accumulated protein deposits ready to use by plants, animals and humans.