Specificity Protein 8 (SP8)

Human SP8 protein contains 466 amino acids, shares 97% identity with the mouse protein. In situ hybridization of day-8 mouse embryos detected Sp8 in the forming neural tube. At later stages, Sp8 localized predominantly in neural tissues and in the apical ectodermal ridge (AER) of fore- and hindlimb buds.The deduced 486-amino acid protein contains an N-terminal serine-threonine domain, followed by an alanine-rich sequence, a glycine-rich sequence, a Btd domain, and SP1-like zinc fingers. Mouse Sp8 mediates proximodistal outgrowth of the limb during early development. They presented evidence that Sp8 is required to maintain, but not to initiate, Wnt /beta-catenin-dependent Fgf -, Shh-, and Bmp-mediated signaling.