Characterization of TPB. (A) Tetrahymena nuclear developmental process during conjugation. (B) Schematic representation of Tpb proteins. (C) Comparison of the catalytic DDD-motif of Tpb2p and other piggyBac-like proteins. The DDD-motif of T. ni piggyBac consisting of D268, D346, and D447 is indicated. (D) Expression of TPB2 by quantitative RT-PCR. Total RNA extracted from vegetative (V), starved (S), and conjugating cells (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 h after postmixing) were used as templates. Quantification was normalized with α-tubulin mRNA expression.