RNA LIGANDS TO HUMAN NERVE GROWTH-FACTOR

High affinity RNA ligands to human nerve growth factor (NGF) were sele cted from pools of random RNA using SELEX [Tuerk, C. and Gold, L, (199 0) Science, 249, 505-510], Nerve growth factor, which is a protein req uired for the development of neurons, is not known to bind nucleic aci ds as part of its natural function, We describe two of the selected RN A molecules in detail, One of them is highly structured, folding into a pseudoknot with an additional hairpin-loop; this structure provides salt-resistant binding to NGF, The other is unstructured and elevated salt concentrations inhibit its binding, These molecules compete with each other for NGF binding, Our RNAs may furnish useful diagnostic too ls for the study of an important neurotrophic protein; additionally, t hey illustrate another example of the potential for nucleic acids to t ake part in novel binding interactions.