The tetratricopeptide repeat (TPR) motif is a protein-protein interaction module
found in multiple copies in a number of functionally different proteins that facilitates
specific interactions with a partner protein(s). Three-dimensional structural
data have shown that a TPR motif contains two antiparallel a-helices such that
tandem arrays of TPR motifs generate a right-handed helical structure with an
amphipathic channel that might accommodate the complementary region of a
target protein. Most TPR-containing proteins are associated with multiprotein
complexes, and there is extensive evidence indicating that TPR motifs are
important to the functioning of chaperone, cell-cycle, transcription, and protein
transport complexes. The TPR motif may represent an ancient protein-protein
interaction module that has been recruited by different proteins and adapted for
specific functions