Tetratricopeptide repeat protein 1 (TTC1) is comprised of 292 amino acids with 3 TPR motifs, such as a Galpha16-binding protein. This interaction is confirmed both in vitro and in transfected mammalian cells, where TTC1 also binds to a number of other Galpha proteins. TTC1 interacts with Ha-Ras especially in its active form. TTC1 also interacts with the GAP domain of NF1.