Ragulator complex protein LAMTOR3

LAMTOR3 (ragulator complex protein LAMTOR3) is a 124-amino-acid protein that functions as a key component of the Ragulator complex, which senses amino acid availability and activates mTORC1 signaling (UniProt: Q9UHA4). Within the complex, LAMTOR3 acts as a guanine nucleotide exchange factor for Rag GTPases and recruits them to lysosomal membranes, enabling mTORC1 recruitment and subsequent activation—a pathway central to cell growth regulation in response to amino acids, growth factors, and energy status (UniProt: Q9UHA4).

LAMTOR3 operates primarily at the lysosome and integrates amino acid sensing with mTORC1-dependent signaling. The protein shows no annotated disease associations in UniProt curated data (UniProt: Q9UHA4).

In Alzheimer's Disease, LAMTOR3 shows ambiguous regulation across subcellular fractions of post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change near zero (0.0227) (Chaparral AD proteomics). The lack of consistent directional change across the four examined fractions (P2, P3, S2, S3) suggests variable subcellular localization changes or no robust global dysregulation of this protein in AD pathology.