Trypanosomatid P in1‐Type Peptidyl‐Prolyl Isomerase Is Cytosolic and Not Essential for Cell Proliferation

P in1‐type peptidyl‐prolyl cis/trans isomerases ( PPI ases) isomerise the peptide bond of specific phosphorylated (Ser/Thr)‐Pro residues, regulating various cellular events. Previously, we reported a P in1‐type PPI ase in T rypanosoma cruzi , but little is known about its function and subcellular localization. Immunofluorescence analysis revealed that in contrast with P in1‐like proteins from diverse organisms, Tc P in1 mainly localized in the cytoplasm and was excluded from the nuclei. In addition, RNAi ‐mediated downregulation of Tb P in1 in T rypanosoma brucei did not abolish cell proliferation. Using yeast two‐hybrid assay, we identified a MORN domain‐containing protein as putative P in1‐binding partners. These data suggest that P in1‐mediated signaling mechanism plays a different role in protozoan parasites.