In this study we have characterized cDNA clones corresponding to a gene, called tpr, that has been implicated in the activation of the met and raf proto-oncogenes. Sequencing of tpr clones isolated from an HT1080 human fibrosarcoma cell line cDNA library identified an open reading frame (ORF) of 726 amino acids. In addition we have established that alternative splicing can result in the deletion of a 30 bp sequence that spans the translation termination site of this ORF. This modification generates mRNAs encoding a tpr protein that has an extended C-terminal domain. The 726 amino acid tpr protein is predicted to have extensive regions of alpha-helix and has three stretches of a heptad repeat motif that is characteristic of proteins adopting a coiled-coil conformation. The tpr protein exhibits weak homology (28-39%) to the alpha-helical domains of several proteins including tropomyosin, spectrin, laminin B1, the Drosophila glued protein and the tail region of myosin heavy chain.