The procyclic stage in the life cycle of African trypanosomes is adapt
ed for life in the harsh environment of the midgut of the tsetse fly v
ector. Procyclic forms derived by transformation from antigenically di
stinct bloodstream variants are antigenically similar and have lost th
e variant surface glycoprotein coat of the bloodstream forms. In contr
ast to bloodstream forms, where the variant surface glycoprotein coat
is essentially the only molecule exposed, many different proteins can
be labeled by surface iodination or biotinylation of procyclic trypano
somes. Despite this multiplicity of procyclic surface proteins, only a
few have been characterized in any detail. This minireview focuses on
one set of them, the predominant procyclins. (C) 1994 Academic Press,
Inc.