Insulin Like Protein 6 (INSL6)

INSL6 contains a classical signature of the insulin superfamily and is significantly similar to relaxin and relaxin-like factor. This gene is preferentially expressed in testis. Its expression in testis is restricted to interstitial cells surrounding seminiferous tubules, which suggests a role in sperm development and fertilization.

The deduced 213-amino acid protein, which shares 45% sequence identity with the mouse protein, contains the classic B-C-A domain configuration, including the 6 cysteines in the B and A domains, of the insulin/relaxin family proteins. Northern blot analysis revealed expression of a 1.2-kb transcript confined to testis. Immunohistochemical analysis demonstrated expression restricted to interstitial cells in mouse testis.