Cell surface components of Leishmania: identification of a novel parasite lectin?

Protozoan parasites of the genus Leishmania have a glycoconjugate surface coat (the glycocalyx) that acts as the interface between the parasite and its external environment. The principal components of the glycocalyx, the lipophosphoglycans and the glycoinositolphospholipids, have a variety of functions that facilitate parasite survival in both the extracellular and the intracellular stages of the life cycle. Recently, a novel hydrophilic Leishmania protein, the Gene B protein, has been identified on the surface of infective parasite stages. Attachment to the surface appears to be by association between a region of repeated amino acids in this molecule and components of the glycocalyx. As a consequence, the Gene B protein is exposed on the parasite surface while other peptides are buried beneath the glycocalyx. The putative functions of this unusual molecule are discussed.