Sonic Hedgehog: Difference between revisions

The tetrahedrally coordinated zinc ion of Shh-N, along with the non-coordinating residues thought to assist hydrolysis, are highly conserved among vertebrate Hh proteins. A potential hydrolytic activity is therefore expected to play an important cellular role. In pursuit of a substrate for Shh-N, it was found that <scene name='Sandbox_191/Scene3/6'>Ala 194 and Lys 195</scene> near the C-terminus of one Shh-N molecule can hydrogen bond with residues in the zinc binding site of a second Shh-N molecule. This indicates that the protein may be capable of cleaving between Lys 195 and Ser 196 within its own C-terminus <ref name="Palm"/>. This is the most highly conserved region of Hh proteins<ref>PMID: 8807822</ref>, and the suspected hydrolytic function of Shh-N has been suggested to liberate the tethered protein from the cell membrane to facilitate long-range signaling <ref name="Palm"/>. However, other possible substrates for Shh-N proteolysis are also likely, including an Shh receptor or other signaling proteins involved in the Shh pathway.