Alveolins, a New Family of Cortical Proteins that Define the Protist Infrakingdom Alveolata

Mol Biol Evol. 2008 Mar 21 [Epub ahead of print]

Alveolins, a New Family of Cortical Proteins that Define the Protist Infrakingdom Alveolata

Gould SB, Tham WH, Cowman AF, McFadden GI, Waller RF.

School of Botany, University of Melbourne, VIC 3010, Australia.

Alveolates are a recently recognised group of unicellular eukaryotes that unites disparate protists including apicomplexan parasites (which cause malaria and toxoplasmosis), dinoflagellate algae (which cause red tides and are symbionts in many corals) and the ciliates (which are microscopic predators and common rumen symbionts). Gene sequence trees provide robust support for the alveolate alliance but beyond the common presence of membranous sacs (alveoli) subtending the plasma membrane the group has no unifying morphological feature. We describe a family of proteins, alveolins, associated with these membranous sacs in apicomplexa, dinoflagellates and ciliates. Alveolins contain numerous simple peptide repeats and are encoded by multi gene families. We generated antibodies against a peptide motif common to all alveolins and identified a range of apparently abundant proteins in apicomplexans, dinoflagellates and ciliates. Immunolocalization reveals that alveolins are associated exclusively with the cortical regions of apicomplexa, dinoflagellates and ciliates where the alveolar sacs occur. Alveolins are the first molecular nexus between the unifying structures that defines this eukaryotic group. They provide an excellent opportunity to explore the exceptional compartment that was apparently the key to a remarkable diversification of unique protists that occupy a wide array of lifestyle niches.

PMID: 18359944 [PubMed - as supplied by publisher]