In host infection processes, the basic M17 LAP from the parasite T. brucei (TbLAP-B) could have some of the following functions: provide an essential amino acid (leucine is a precursor for sterol biosynthesis [18, 19]), being involved in infectivity [20], regulate stress responses and signal transduction [21], act as protein chaperones [22], be required for glutathione metabolism [23], and participate in host cell invasion [24, 25]. Here, LAP3 is linked to infection.