CRNF, A MOLLUSCAN NEUROTROPHIC FACTOR THAT INTERACTS WITH THE P75 NEUROTROPHIN RECEPTOR

A 13.1-kilodalton protein, cysteine-rich neurotrophic factor (CRNF), w as purified from the mollusk Lymnaea stagnalis by use of a binding ass ay on the p75 neurotrophin receptor. CRNF bound to p75 with nanomolar affinity but was not similar in sequence to neurotrophins or any other known gene product. CRNF messenger RNA expression was highest in adul t foot subepithelial cells; in the central nervous system, expression was regulated by lesion. The factor evoked neurite outgrowth and modul ated calcium currents in pedal motor neurons. Thus, CRNF may be involv ed in target-derived trophic support for motor neurons and could repre sent the prototype of another family of p75 ligands.