Leishmania Surface Proteins
Emanuela Handman, Anthony T. Papenfuss, Terence P. Speed and James W. Goding
from: Leishmania: After The Genome (Edited by: Peter J. Myler and Nicolas Fasel). Caister Academic Press, U.K. (2008)
Leishmania are polarized flagellated cells with surface membrane domains of distinct composition and function. Specific surface proteins are distributed on the flagellum, the flagellar pocket and around the cell body, and they contribute to the functional specialization of these regions. The Leishmania genome database suggests that a few hundred different proteins are expected to be displayed on the parasite surface, but the number of well-characterised proteins has been disappointingly small. The best characterized proteins are anchored into the membrane with GPI anchors. Much less is known about those that are held in the membrane with stretches of hydrophobic amino acids. The well-characterized surface proteins include ligands for the insect or the mammalian host. Remarkably, some of these proteins are heavily decorated with complex glycans that are similar or identical to those found on lipophosphoglycans that contain no protein. Knowledge of the genomes of several Leishmania species, as well as those of T. brucei and T. cruzi , combined with the rapid development of algorithms for use in bioinformatics is providing tools of extraordinary power for the identification of the genes encoding all membrane proteins. However, as has been the case with most other eukaryotic genomes, a large percentage of predicted proteins have not yet been assigned a function. This remains the major challenge of the post-genomic era. New developments in gene deletion, modulation and over-expression will greatly facilitate the task. However, enthusiasm for a large-scale "global" or "systems" approach to membrane proteins should be moderated by knowledge that the remarkably diverse post-translational modifications seen in Leishmania and other species cannot be predicted from gene sequences. Biochemistry, cell biology and physiology are not obsolete. We will still need to study proteins of interest in detail, one by one read more ...