The function of ELFN1 (extracellular leucine rich repeat and fibronectin type III domain containing 1, Ensembl gene identifier ENSG00000225968) is as follows. Postsynaptic protein that regulates circuit dynamics in the central nervous system by modulating the temporal dynamics of interneuron recruitment. Specifically present in excitatory synapses onto oriens-lacunosum molecular (OLM) interneurons and acts as a regulator of presynaptic release probability to direct the formation of highly facilitating pyramidal-OLM synapses (By similarity). Inhibits phosphatase activity of protein phosphatase 1 (PP1) complexes. .