Phostensin has been identified as a PP1 regulatory protein binding protein. This domain is N-terminal to the PP1- and SH3-binding regions though may carry an additional SH3-binding motif. It is likely that Phostensin targets PP1 to the F-actin cytoskeleton [1]. Phostensin binds to actin and decreases the elongation and depolymerisation rates of actin filament pointed ends [2].

1: Identification of phostensin, a PP1 F-actin cytoskeleton targeting subunit. Kao SC, Chen CY, Wang SL, Yang JJ, Hung WC, Chen YC, Lai NS, Liu HT, Huang HL, Chen HC, Lin TH, Huang HB; Biochem Biophys Res Commun. 2007;356:594-598. PMID:17374523

2: Phostensin caps to the pointed end of actin filaments and modulates actin dynamics. Lai NS, Wang TF, Wang SL, Chen CY, Yen JY, Huang HL, Li C, Huang KY, Liu SQ, Lin TH, Huang HB; Biochem Biophys Res Commun. 2009;387:676-681. PMID:19622346