UC San Diego
Bioinformatic Characterization of the Trimeric Intracellular Cation-specific (TRIC) Channel Protein Family
- Author(s): Silverio, Abe Legaspi Fonte
- Advisor(s): Saier, Milton H
- et al.
Trimeric Intracellular Cation-specific (TRIC) channels are integral in excitation-contraction coupling. TRIC channels provide counter ionic flux when calcium is rapidly transported from intracellular stores to the cell cytoplasm. Until recently, the presence of these proteins was limited to animals. We have analyzed the TRIC family and have identified a profusion of prokaryotic family members with the same topologies and motifs similar to those of their eukaryotic counterparts. Prokaryotic members far outnumber eukaryotic members, and although none has been functionally characterized, the evidence suggests that they are functional. The presence of fused N- or C- terminal domains of known biochemical functions as well as genomic context analyses provides clues about the functions of their prokaryotic homologs. Phylogenetic analysis revealed that TRIC channel homologs diverged relatively early during evolutionary history and that horizontal gene transfer was frequent in prokaryotes but not eukaryotes. Topological analyses of TRIC channels revealed that these proteins possess seven putative transmembrane segments (TMS). We demonstrate that TRIC channels arose by intragenic duplication of a three TMS-encoding polypeptide chain yielding a six TMS protein and the addition of a seventh TMS at the C terminal end to give a seven TMS protein, the precursor of all current TRIC family homologs.
The Abstract, in full, is being submitted for publication. The thesis author will be the primary investigator and author of this paper.