May play a role as ligand of RXFP1. Homotrimer (PubMed:19666007). Forms heteromeric complexes with C1QL1 (PubMed:19666007). Interacts with RXFP1 (PubMed:24014093). Expressed predominantly in lung and testis (PubMed:19666007). Expressed in astrocytes (PubMed:24014093). Not N-glycosylated. Contains a 30 bp insertion which does not match the genome. Contains a 30 bp insertion which does not match the genome.