Abstract
Protein catabolism is of major importance for cell physiology. It is responsible for the elimination of peptides, the accumulation of which would turn out to be toxic. It is also involved in the control of key steps of cell differentiation and proliferation. Moreover, it is at the origin of the specific immune response through the production of antigenic peptides. We have previously detailed the intimate mechanisms of protein degradation (m/s n degrees 6, vol. 11, p. 723). Herein, we present examples of regulated degradation along with the processes involved in the production of peptides presentable by the major histocompatibility complex molecules.