5 research outputs found
Ciliate pheromone structures and activity: a review
As in animals and other multicellular organisms, protozoan ciliates communicate via diffusible signalling pheromones.
These pheromones have been identified in the culture supernatant of various species. However, their isolation and definitive
structural characterization have been achieved only in species of Blepharisma and Euplotes. With the exception of the two B.
japonicum pheromones represented by a tryptophan-related molecule and a glycoprotein, all the other pheromones isolated
from Euplotes species are proteins that vary in extension between 38 and 109 amino acids. They form species-specific
families of structurally homologous members, in full accord with their multi-allelic determination at an apparently single
genetic locus. The determination of the Nuclear Magnetic Resonance (NMR) solution structures of E. raikovi and E. nobilii
pheromones has provided direct evidence that, although structurally unique, Euplotes pheromones adopt a common, speciesspecific
three-helix folding. This close structural homology among members of the same family well accounts for the
pheromone capacity to compete with one another in cell receptor binding reactions and elicit context-dependent, autocrine
(growth-promoting) or paracrine (mating-inducing) cell responses