The tetratricopeptide repeats of Ssn6 interact with the homeo domain of alpha 2.

The tetratricopeptide repeat (TPR) is a 34-amino-acid degenerate sequence motif that is found in a large variety of proteins, both prokaryotic and eukaryotic. TPRs are usually found in tandem arrays of up to 16 copies. In this paper we identify a direct interaction between the TPRs of Ssn6, a general transcriptional repressor, and alpha 2, a cell-type regulator in Saccharomyces cerevisiae. Five of the Ssn6 TPRs were tested individually, and all were found to interact specifically with alpha 2. These results suggest a model for TPR-protein interactions and for the role that a tandem array of TPRs may have in mediating transcriptional repression.