| 背景信息 |
TSC complex subunit 1 (TSC1), also known as hamartin, is a tumor suppressor protein that plays a crucial role in regulating cell growth and proliferation. TSC1 forms a multi-protein complex with TSC2 (tuberin) and TBC1D7, creating an elongated, scorpion-like structure where TSC1’s coiled-coil backbone runs along the TSC2 dimer, breaking its symmetry and facilitating complex assembly. This complex acts as a GTPase-activating protein (GAP) for the small GTPase Rheb, thereby negatively regulating the mammalian target of rapamycin complex 1 (mTORC1), a central controller of anabolic cell growth. TSC1 also functions as a co-chaperone for Hsp90, inhibiting its ATPase activity and stabilizing client proteins, including TSC2, by preventing their ubiquitination and proteasomal degradation. Mutations in TSC1 disrupt these regulatory functions, leading to diseases such as tuberous sclerosis complex—a genetic disorder characterized by benign tumor growth in multiple organs—and lymphangioleiomyomatosis. |