Tripartite Motif Containing Protein 66 (TRIM66)

Tif1d repressed transcriptional activation of a chimeric activator. Using trichostatin A treatment, they determined that Tif1d repressor activity is mediated by recruitment of deacetylase activity. The deduced 1,344-amino acid mouse protein shares similarity with Tif1a, Tif1b (TRIM28), and Tif1g (TRIM33). Tif1d contains an N-terminal RBCC (N-terminal RING/B-box/coiled-coil) motif, a C-terminal bromodomain preceded by a PHD finger, and a 39-amino acid central region similar to the HP1 box of Tif1a and Tif1b. Northern blot analysis of mouse tissues detected expression primarily in testis. Immunofluorescence studies localized Tif1d protein to nuclei of postmeiotic, haploid, and elongating spermatids. Western blot analysis detected Tif1d protein in mouse testis from 4 weeks of age onward.