Detection of phosphoinositide-binding proteins in Tetrahymena vorax
using liposomes as an affinity matrix
Thomas M. Yarbrough and Phillip E. Ryals
Department of Biology
Tetrahymena vorax, a unicellular eukaryotic organism, was used to identify the presence of
proteins that bind to inositol-containing phospholipids. T. vorax can be induced by stomatin
to differentiate from a microstomal cell to a macrostomal cell, allowing them to engulf larger
cells. Cultures of T. vorax were homogenized at mid-logarithmic growth phase, and their
microsomal fractions isolated by ultracentrifugation, carbonate extraction, and dialysis.
Microsomal protein samples were incubated with control liposomes containing four lipids
common to all eukaryotes and experimental liposomes containing the same lipids in addition
to a phosphoinositide. Samples were run on polyacrylamide gel electrophoresis and stained
with SYPRO-Ruby. Preliminary results show two bands with molecular weights of 44 kDa
and 49.5 kDa in the experimental lanes that are greater in intensity than the control lanes,
suggesting phosphoinositide-binding proteins are evident in the microsomal protein samples.
Further investigation of phosphoinositide-binding proteins is planned using macrostomal
populations and temperature treated microstomal populations of Tetrahymena patula.
Phosphoinositide-binding proteins are likely to be involved in the differentiation process of
Tetrahymena spp., and their presence may provide clues to a better understanding of the
mechanism controlling differentiation.