This domain has been predicted to be involved in protein-protein interaction [1]. This domain was recently shown to bind the hyperphosphorylated C-terminal repeat domain of RNA polymerase II, confirming its role in protein-protein interactions [2].

1: The FF domain: a novel motif that often accompanies WW domains. Bedford MT, Leder P; Trends Biochem Sci 1999;24:264-265. PMID:10390614

2: Protein-interaction modules that organize nuclear function: FF domains of CA150 bind the phosphoCTD of RNA polymerase II. Carty SM, Goldstrohm AC, Sune C, Garcia-Blanco MA, Greenleaf AL; Proc Natl Acad Sci U S A 2000;97:9015-9020. PMID:10908677