Animal-free Recombinant Human SHH (Sonic Hedgehog) protein is the orthologue of drosophila hedgehog (Hh) and plays a critical role in vertebrate limb development. SHH gene encodes for a 45 kDa protein that undergoes autoproteolysis activated by its own C-terminal domain. Furthermore, the C-terminal domain also carries out cholesterol transferase activity. This auto-cleavage results in the formation of a 174 amino acid N-terminal product with covalently linked cholesterol moiety and a palmitoyl modification. The presence of the cholesterol and palmitoyl moieties is required for the activity of the mature SHH protein. These modifications are found in SHH derived from human cells, but are absent in bacterially expressed SHH. The N-terminal (active) form of SHH shares 98% aa homology to mouse, rat, canine, porcine and chicken SHH. It has been associated with tissue regeneration following injury and development of certain cancers in adults.
SHH, also named as HHG-1, belongs to the hedgehog family. SHH binds to the patched receptor (PTC), that in association with smoothened (SMO) activate the transcription of target genes. In the absence of SHH, PTC represses the constitutive signaling activity of SMO. SHH is synthesized as a 45 kDa protein precursor that is autocatalytically cleaved to yield of 20 kDa N-terminal fragment (24-197 in the human gene sequence) knowing as being responsible for all known hedgehog biological activity and a 25 kDa C-terminal fragment that contains the auto-processing machinery (PMID:10753901).