This short motif is about 40 amino acids in length. In the Fip1 protein that is a component of a yeast pre-mRNA polyadenylation factor that directly interacts with poly(A) polymerase [1]. This region of Fip1 is needed for the interaction with the Th1 subunit of the complex and for specific polyadenylation of the cleaved mRNA precursor [2].

1: The FIP1 gene encodes a component of a yeast pre-mRNA polyadenylation factor that directly interacts with poly(A) polymerase. Preker PJ, Lingner J, Minvielle-Sebastia L, Keller W; Cell 1995;81:379-389. PMID:7736590

2: Fip1 regulates the activity of Poly(A) polymerase through multiple interactions. Helmling S, Zhelkovsky A, Moore CL; Mol Cell Biol 2001;21:2026-2037. PMID:11238938