These have been identified as inhibitors of the Ras/mitogen-activated protein kinase (MAPK) cascade, a pathway crucial for developmental processes initiated by activation of various receptor tyrosine kinases.
[1][2] These proteins share a conserved, C-terminal cysteine-rich region, the SPR domain.
[2][3][4][5] It has been found to be a PtdIns(4,5)P2-binding domain that targets the proteins to a cellular localization that maximizes their inhibitory potential.
[3][6] The SPR domain can occur in association with the WH1 domain (see InterPro: IPR000697) (located in the N-terminus) in the Spred proteins.
Human genes encoding protein containing the SPR domain include: