Intracellular protein degradation in Leishmania tropica promastigotes

A labile class of proteins in the range of M_r = 30 000–60 000 which turn over rapidly have been demonstrated in Leishmania tropica promastigotes. The rate of protein degradation is increased by exhaustion of nutrients or inhibition of energy metabolism. Proteolysis is reduced when the parasites are provided with a readily utilizable carbon and energy source such as glucose, glutamate or proline. The breakdown of proteins in L. tropica is dependent on continuous protein synthesis probably for protease synthesis. It is suggested that the relatively high rate of intracellular protein degradation is an auxiliary means for generating carbon and energy sources during nutritional stress.