The function of IGSF1 (immunoglobulin superfamily member 1, ENSG00000147255) is as follows. Seems to be a coreceptor in inhibin signaling, but seems not to be a high-affinity inhibin receptor. Antagonizes activin A signaling in the presence or absence of inhibin B (By similarity). Necessary to mediate a specific antagonistic effect of inhibin B on activin- stimulated transcription. .