Inhibits the binding of prostaglandin F2-alpha (PGF2-alpha) to its specific FP receptor, by decreasing the receptor number rather than the affinity constant. Functional coupling with the prostaglandin F2-alpha receptor seems to occur (By similarity). In myoblasts, associates with tetraspanins CD9 and CD81 to prevent myotube fusion during muscle regeneration. Interacts with CD9 and CD81 (By similarity). Part of a complex composed of CD9, CD81 and IGSF8 (PubMed:23575678). Also seems to interact with CD63, CD82 and CD151 (By similarity). Expressed in myoblasts (at protein level).