Folliculin Interacting Protein 2 (FNIP2)

FNIP2 bound directly to FLCN and appeared to bind more tightly to phosphorylated FLCN. Truncation analysis revealed that FNIP2 and FLCN interacted via their C-terminal regions. When expressed alone, FLCN localized to the nucleus, but when coexpressed with FNIP1 or FNIP2, the coexpressed proteins localized to the cytoplasm in a reticular pattern. Cytoplasmic retention of FLCN was countered by C-terminal truncation of FNIP2.

The deduced 1,114-amino acid protein shares 49% identity with FNIP1. Quantitative real-time PCR detected variable FNIP2 expression in most tissues examined, with highest expression in fat, liver, pancreas, and salivary gland. Epitope-tagged FNIP2 localized in the cytoplasm in a reticular pattern.The deduced protein contains 1,139 amino acids.