Trypanosoma brucei causes human African trypanosomiasis (HAT). The diseasethreatens over 60 million people in 36 African countries. Chemotherapy is the only method oftreatment available against HAT. Generally, the drugs are toxic and difficult to administer.Today, the need for safer, orally administered drugs is urgent.T. brucei is covered with a glycosyl phosphatidylinositol (GPI)-anchored variant surfaceglycoprotein (VSG). VSG is essential for the viability of T. brucei in the hosts bloodstream.The parasite also expresses a GPI-specific phospholipase C that is able to cleave the GPI-anchorof VSG. Interestingly, little VSG is released in non-differentiating bloodstream cells. Theintracellular localization of GPI-PLCp is not well characterized and the function(s) of theenzyme are just beginning to be elucidated. To gain better perspective of the functions of GPIPLCp,it is important to determine the intracellular location of the enzyme.Tyrosine kinase activity is present in T. brucei. Preliminary investigations suggest thatdrugs that inhibit protein tyrosine kinases (PTKs) kill the parasite. Given their role in cancer,PTKs have become the focus of an enormous effort to discover new drugs against the disease.Several drugs that inhibit PTKs have been developed and are being used to treat some cancers.The goal of this dissertation is two-fold. First, to further understand the function of GPIPLCpin T. brucei, we aimed to determine the intracellular location of the enzyme. Towards this,we used two approaches; (i) fluorescence microscopy, and (ii) iodixanol density-gradientcentrifugation and found GPI-PLCp to be a glycosome protein. In a second project, we wantedto determine if PTK-specific drugs used to treat cancer could kill T. brucei. To this end, wetreated T. brucei with the drugs Canertinib, PKI166 and AEE788 and found that all kill culturedtrypanosomes. Further we found AEE788, a pyrrolopyrimidine, to be the most potent drugtested and within 90 minutes of exposure it: (i) reduces tyrosine phosphorylation, (ii) blocksendocytosis of transferrin, (iii) causes a morphological change, and (iv) triggers cell death in T.brucei. Finally, to understand which processes may be influenced by tyrosine phosphorylation inbloodstream T. brucei, we identified tyrosine-phosphorylated proteins by pTyr-affinitychromatography and LC-MS/MS. Using this technique, we identified 132 putative pTyr proteinsand two proteins with confirmed pTyr residues. Collectively, these data validate PTKs as targetsfor drug discovery in T. brucei and introduce pyrrolopyrimidines as a lead scaffold for antitrypanosomedrug discovery.