The relaxin-like peptide family belongs in the insulin superfamily and consists of 7 peptides of high structural but low sequence similarity; relaxin-1 (RLN1), 2 (RLN2) and 3 (RLN3), and the insulin-like (INSL) peptides, INSL3, INSL4, INSL5 and INSL6.
La relaxina fa parte di una super-famiglia di 7 peptidi simil-relaxina ad alta somiglianza strutturale ma scarsa similitudine aminoacidica tra loro; essi sono: relaxina-1 (RLN1), 2 (RLN2) e 3 (RLN3), e i peptidi simil-insulinici (INSL), INSL3, INSL4, INSL5 e INSL6.