Role in Presence and Absence of Hedgehog Signaling
Patched is part of a negative feedback mechanism for Hedgehog signaling that helps shape the spatial gradient of signaling activity across tissues. In the absence of hedgehog, low levels of patched are sufficient to suppress activity of the signal transduction pathway. When Hedgehog is present and binds to Patched, Patched somehow inhibits the activity of Smoothened, a G protein-coupled receptor, most of which is stored in membrane bound vesicles internally within the cell and which increases at the cell surface when Hedgehog is present. Smoothened must be present on the cell membrane in order for the Hedgehog signaling pathway to be activated. Among other genes, the transcription of the patched gene is induced by Hedgehog signaling, with the accumulation of the Patched protein limiting signaling through the Smoothened protein. Recent work implicates the cilium in intracellular trafficking of Hedgehog signaling components in vertebrate cells.
Read more about this topic: Patched
Famous quotes containing the words role in, role, presence and/or absence:
“My role in society, or any artist or poet’s role, is to try and express what we all feel. Not to tell people how to feel. Not as a preacher, not as a leader, but as a reflection of us all.”
—John Lennon (1940–1980)
“To win by strategy is no less the role of a general than to win by arms.”
—Julius Caesar [Gaius Julius Caesar] (100–44 B.C.)
“The sun rarely shines in history, what with the dust and confusion; and when we meet with any cheering fact which implies the presence of this luminary, we excerpt and modernize it.”
—Henry David Thoreau (1817–1862)
“The absence of the beloved, short though it may last, always lasts too long.”
—Molière [Jean Baptiste Poquelin] (1622–1673)