Development of mating competency in Tetrahymena thermophila requires
starvation for at least 70 min in low ionic strength
buffer. Pair formation between conjugating cells is blocked at early stages by the
lectin Concanavalin A (Con A). To investigate the role of
Con A-binding proteins in this induced cellular change and pairing, and to confirm and extend an earlier study from our laboratory, a method was developed for preparation of
Con A-binding proteins from ciliary membrane-rich fractions of T. thermophila. Con A-binding ciliary
proteins were prepared from non-starved and starved cells from two wild type strains and a mating mutant, RH179E1. Comparison of these
proteins by SDS-PAGE revealed on overall reduction in number of wild-type bands after
starvation. In particular, a major band at 28 kDa was present in non-starved cells and absent in starved cells. However, in the mating mutant, no change in banding profile was seen after
starvation: the 28 kDa band was present in both non-starved and starved cells. This, Con A-binding ciliary
membrane proteins undergo a major change during
starvation-induced development of mating competency in wild-type T. thermophila. In contrast, the mutant differed from wild-type in overall composition of its ciliary
Con A-binding glycoproteins and in the response of these
proteins to
starvation, suggesting that it may be deficient in its ability to be initiated by
starvation. Our results are consistent with the hypothesis that a change affecting ciliary membrane
Con A-binding proteins is essential for the cellular response to mating signals.