Vesicle trafficking between organelles occurs through fusion of dormer and
specific acceptor membranes. This process is highly regulated and ensures p
roper direction in sorting and packaging of a number of molecules in eukary
otic cells. Monomeric GTPases of the Rab family play a pivotal role in the
control of membrane fusion and vesicle traffic. In this paper, we character
ize a Trypanosoma cruzi Rab11 homologue (TcRab11) that shares at, the amino
acid level, 40% similarity with human rab11, Arabdopsis thaliana rab11 and
yeast rab11 homologue genes. Western blot analysis, using a polyclonal rab
bit antiserum raised against a synthetic peptide derived from the COOH-term
inus of predicted the TcRab11 protein, reacted to a 26 kDa protein. In immu
nofluorescence assays, TcRab11, was shown to be expressed in epimastigote a
nd amastigote forms, but it was absent in trypomastigotes. Interestingly, t
he TcRab11 product seems to be located at the reservosome complex, a site o
f active endocytosis and Vesicle fusion present only in the epimastigote st
age. Therefore, TcRab11 may represent the first molecular marker of this pe
culiar organelle. (C) 2000 Elsevier Science B.V. All rights reserved.