Final answer:
PTCH functions in inhibiting smoothened by deactivating the smoothened protein, which obstructs downstream signaling in the hedgehog pathway, thereby playing a critical role in various developmental processes.
Step-by-step explanation:
The function of PTCH ("patched") in inhibiting smoothened is that it plays a crucial role in deactivating the smoothened protein. PTCH is a transmembrane protein responsible for repressing the activity of the smoothened protein. When PTCH is activated, it prevents smoothened from signaling downstream target genes thus inhibiting the hedgehog signaling pathway. This regulation is critical in various developmental processes and its deregulation can lead to several human diseases, including cancers.
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