KPTN

This gene encodes a filamentous-actin-associated protein, which is involved in actin dynamics and plays an important role in neuromorphogenesis. This protein is part of the KICSTOR protein complex that localizes to lysosomes. Mutations in this gene result in an autosomal recessive form of intellectual disability. Alternatively spliced transcript variants have been found for this gene.

Kaptin, Actin Binding Protein

As part of the KICSTOR complex functions in the amino acid-sensing branch of the TORC1 signaling pathway. Recruits, in an amino acid-independent manner, the GATOR1 complex to the lysosomal membranes and allows its interaction with GATOR2 and the RAG GTPases. Functions upstream of the RAG GTPases and is required to negatively regulate mTORC1 signaling in absence of amino acids. In absence of the KICSTOR complex mTORC1 is constitutively localized to the lysosome and activated. The KICSTOR complex is also probably involved in the regulation of mTORC1 by glucose.

Actin filament organizationIEA:InterPro
Cellular response to amino acid starvationManual Assertion Based On ExperimentIMP:UniProtKB
Cellular response to glucose starvationManual Assertion Based On ExperimentIMP:UniProtKB
Negative regulation of TORC1 signalingManual Assertion Based On ExperimentIMP:UniProtKB
Protein localization to lysosomeManual Assertion Based On ExperimentIMP:UniProtKB

Lysosome membrane
Cell projection, lamellipodium
Cell projection, stereocilium
Localization to lysosomes is amino acid-independent (PubMed:28199306).
Colocalizes with F-actin (PubMed:24239382).

Mental retardation, autosomal recessive 41 (MRT41):
A disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. MRT41 most consistent features are global developmental delay, macrocephaly with frontal bossing, high levels of anxiety, and some features suggestive of a pervasive developmental disorder. Less common features include fifth finger clinodactyly, recurrent pneumonia, and hepatosplenomegaly.