Reproducible and variable rearrangements of a Tetrahymena thermophila surface protein gene family occur during macronuclear development.

The expression of Tetrahymena surface proteins serotype H3 (SerH3) and serotype T (SerT) is under environmental regulation. SerH3 is expressed when cells are incubated between the temperatures of 20 and 35 degrees C, while SerT is expressed when cells are grown at temperatures above 35 degrees C. Using a SerH3 cDNA clone as a hybridization probe, we determined that (i) the SerH3 gene is a member of a multigene family; (ii) most members of this multigene family are variably rearranged during macronuclear development; and (iii) the gene which produces the SerH3 mRNA is reproducibly rearranged during macronuclear development.