Recombinant Fem-3 mRNA-binding factor 2 (fbf-2) fragment (residues 167-570) from Caenororhabditis elegans, a stable and soluble unit optimized for structural and biochemical studies of RNA-binding mechanisms in germline regulation.

Fem-3 mRNA-binding factor 2 (fbf-2) is an RNA-binding protein from C. elegans that specifically recognizes the 5'-UGUGCCAUA-3' consensus sequence in mRNA 3'-UTRs. It plays critical roles in stem cell control, sex determination, and germline development, including regulating the sperm/oocyte switch by binding the fem-3 3'-UTR, repressing lip-1 phosphatase expression, and suppressing germline tumor formation. The protein localizes to the cytoplasm and cytoplasmic granules, where it is recruited to P granules by dlc-1, and features a C-terminal disordered region that may auto-inhibit RNA binding, potentially reversed by interaction with lst-1. This recombinant fragment (167-570) represents a stable, soluble region ideal for investigating its RNA-binding properties and functional mechanisms.