FNIP1 PrEST Antigen

Protein function: Binding partner of the GTPase-activating protein FLCN: involved in the cellular response to amino acid availability by regulating the mTORC1 signaling cascade controlling the MiT/TFE factors TFEB and TFE3 (PubMed:17028174, PubMed:18663353, PubMed:24081491). In low-amino acid conditions, component of the lysosomal folliculin complex (LFC) on the membrane of lysosomes, which inhibits the GTPase- activating activity of FLCN, thereby inactivating mTORC1 and promoting nuclear translocation of TFEB and TFE3. Upon amino acid restimulation, disassembly of the LFC complex liberates the GTPase- activating activity of FLCN, leading to activation of mTORC1 and subsequent cytoplasmic retention of TFEB and TFE3. Required to promote FLCN recruitment to lysosomes and interaction with Rag GTPases (PubMed:24081491). Together with FLCN, regulates autophagy: following phosphorylation by ULK1, interacts with GABARAP and promotes autophagy (PubMed:25126726). In addition to its role in mTORC1 signaling, also acts as a co-chaperone of HSP90AA1/Hsp90: following gradual phosphorylation by CK2, inhibits the ATPase activity of HSP90AA1/Hsp90, leading to activate both kinase and non-kinase client proteins of HSP90AA1/Hsp90 (PubMed:27353360, PubMed:30699359). Acts as a scaffold to load client protein FLCN onto HSP90AA1/Hsp90 (PubMed:27353360). Competes with the activating co-chaperone AHSA1 for binding to HSP90AA1, thereby providing a reciprocal regulatory mechanism for chaperoning of client proteins (PubMed:27353360). Required for B-cell development. [The UniProt Consortium] Buffer: PBS and 1M Urea, pH 7.4.