protein
Hamartin
Gene
TSC1
Organism
Homo sapiens(9606)
Length
1164 aa
Mass
129,767 Da
# Hamartin (TSC1) Summary
Hamartin is the non-catalytic component of the TSC-TBC complex, which negatively regulates mTORC1, a central nutrient sensor controlling cellular growth and anabolism (UniProt: Q92574). Within the complex, hamartin stabilizes its binding partner TSC2 and acts as a GTPase-activating protein for RHEB to suppress mTORC1 signaling during nutrient scarcity. Additionally, hamartin functions as a co-chaperone for HSP90AA1, modulating its chaperoning activity toward kinases and other client proteins.
Hamartin mutations cause tuberous sclerosis 1 (TSC1), an autosomal dominant disorder characterized by multi-organ hamartomas affecting the brain, kidneys, heart, and skin. Clinical features include intractable seizures, learning difficulties, behavioral problems, and skin manifestations. TSC1 mutations also predispose to lymphangioleiomyomatosis, a progressive lung disease, and focal cortical dysplasia type 2, which presents with medically refractory pediatric epilepsy and cortical malformation.
Hamartin is curated as SFARI Category S syndromic (SFARI Cat S), indicating association with autism spectrum disorder through the context of tuberous sclerosis, a recognized syndromic autism etiology where developmental and neurological complications frequently co-occur with autism features.
Generated from the curated entity record below. May contain errors — verify against source links.
Genetic Evidence · ASD
Source: SFARI Gene database · gene.sfari.org
Related Publications
Browse all →Inherited and De Novo Genetic Risk for Autism Impacts Shared Networks.
Ruzzo Elizabeth K et al.Cell2019PMID 31398340Inherited and multiple de novo mutations in autism/developmental delay risk genes suggest a multifactorial model.
Guo Hui et al.Molecular autism2018PMID 30564305Whole genome sequencing resource identifies 18 new candidate genes for autism spectrum disorder.
C Yuen Ryan K et al.Nature neuroscience2017PMID 28263302Identification of common genetic risk variants for autism spectrum disorder.
Grove Jakob et al.Nature genetics2019PMID 30804558Synaptic, transcriptional and chromatin genes disrupted in autism.
De Rubeis Silvia et al.Nature2014PMID 25363760
Function
Non-catalytic component of the TSC-TBC complex, a multiprotein complex that acts as a negative regulator of the canonical mTORC1 complex, an evolutionarily conserved central nutrient sensor that stimulates anabolic reactions and macromolecule biosynthesis to promote cellular biomass generation and growth (PubMed:12172553, PubMed:12271141, PubMed:12906785, PubMed:15340059, PubMed:24529379, PubMed:28215400). The TSC-TBC complex acts as a GTPase-activating protein (GAP) for the small GTPase RHEB, a direct activator of the protein kinase activity of mTORC1 (PubMed:12906785, PubMed:15340059, PubMed:24529379). In absence of nutrients, the TSC-TBC complex inhibits mTORC1, thereby preventing phosphorylation of ribosomal protein S6 kinase (RPS6KB1 and RPS6KB2) and EIF4EBP1 (4E-BP1) by the mTORC1 signaling (PubMed:12271141, PubMed:24529379, PubMed:28215400, PubMed:33215753). The TSC-TBC complex is inactivated in response to nutrients, relieving inhibition of mTORC1 (PubMed:12172553, PubMed:24529379). Within the TSC-TBC complex, TSC1 stabilizes TSC2 and prevents TSC2 self-aggregation (PubMed:10585443, PubMed:28215400). Acts as a tumor suppressor (PubMed:9242607). Involved in microtubule-mediated protein transport via its ability to regulate mTORC1 signaling (By similarity). Also acts as a co-chaperone for HSP90AA1 facilitating HSP90AA1 chaperoning of protein clients such as kinases, TSC2 and glucocorticoid receptor NR3C1 (PubMed:29127155). Increases ATP binding to HSP90AA1 and inhibits HSP90AA1 ATPase activity (PubMed:29127155). Competes with the activating co-chaperone AHSA1 for binding to HSP90AA1, thereby providing a reciprocal regulatory mechanism for chaperoning of client proteins (PubMed:29127155). Recruits TSC2 to HSP90AA1 and stabilizes TSC2 by preventing the interaction between TSC2 and ubiquitin ligase HERC1 (PubMed:16464865, PubMed:29127155)
Disease associations
Tuberous sclerosis 1TSC1
An autosomal dominant multi-system disorder that affects especially the brain, kidneys, heart, and skin. It is characterized by hamartomas (benign overgrowths predominantly of a cell or tissue type that occurs normally in the organ) and hamartias (developmental abnormalities of tissue combination). Clinical manifestations include epilepsy, learning difficulties, behavioral problems, and skin lesions. Seizures can be intractable and premature death can occur from a variety of disease-associated causes.
LymphangioleiomyomatosisLAM
Progressive and often fatal lung disease characterized by a diffuse proliferation of abnormal smooth muscle cells in the lungs. It affects almost exclusively young women and can occur as an isolated disorder or in association with tuberous sclerosis complex.
Focal cortical dysplasia 2FCORD2
A form of focal cortical dysplasia, a malformation of cortical development that results in medically refractory epilepsy in the pediatric population and in adults. FCORD2 is a severe form, with onset usually in childhood, characterized by disrupted cortical lamination and specific cytological abnormalities. It is classified in 2 subtypes: type IIA characterized by dysmorphic neurons and lack of balloon cells; type IIB with dysmorphic neurons and balloon cells.
Sources
Last updated 5/6/2026, 5:25:05 AM