Receptor tyrosine kinase involved in the development and the maturation of the central and peripheral nervous systems through regulation of proliferation, differentiation and survival of sympathetic and nervous neurons. High affinity receptor for NGF which is its primary ligand (PubMed:1281417, PubMed:15488758, PubMed:17196528, PubMed:1849459, PubMed:1850821, PubMed:22649032, PubMed:27445338, PubMed:8325889). Can also bind and be activated by NTF3/neurotrophin-3.

However, NTF3 only supports axonal extension through NTRK1 but has no effect on neuron survival (By similarity). Upon dimeric NGF ligand-binding, undergoes homodimerization, autophosphorylation and activation (PubMed:1281417). Recruits, phosphorylates and/or activates several downstream effectors including SHC1, FRS2, SH2B1, SH2B2 and PLCG1 that regulate distinct overlapping signaling cascades driving cell survival and differentiation.

Through SHC1 and FRS2 activates a GRB2-Ras-MAPK cascade that regulates cell differentiation and survival. Through PLCG1 controls NF-Kappa-B activation and the transcription of genes involved in cell survival. Through SHC1 and SH2B1 controls a Ras-PI3 kinase-AKT1 signaling cascade that is also regulating survival.

In absence of ligand and activation, may promote cell death, making the survival of neurons dependent on trophic factors

Exists in a dynamic equilibrium between monomeric (low affinity) and dimeric (high affinity) structures. Homodimerization is induced by binding of a NGF dimer (PubMed:10490030, PubMed:1281417, PubMed:17196528). Interacts with SQSTM1; bridges NTRK1 to NGFR (PubMed:11244088).

Forms a ternary complex with NGFR and KIDINS220; this complex is affected by the expression levels of KIDINS220 and an increase in KIDINS220 expression leads to a decreased association of NGFR and NTRK1 (By similarity). Interacts with SH2D1A; regulates NTRK1 (By similarity). Interacts (phosphorylated upon activation by NGF) with SHC1; mediates SHC1 phosphorylation and activation (PubMed:15488758, PubMed:8155326).

Interacts (phosphorylated upon activation by NGF) with PLCG1; mediates PLCG1 phosphorylation and activation (PubMed:15488758, PubMed:7510697). Interacts (phosphorylated) with SH2B1 and SH2B2 (By similarity). Interacts with GRB2 (PubMed:15488758).

Interacts with PIK3R1 (PubMed:15488758). Interacts with FRS2 (PubMed:15488758). Interacts with SORT1; may regulate NTRK1 anterograde axonal transport (PubMed:21102451).

Interacts with RAB7A (By similarity). Found in a complex, at least composed of KIDINS220, MAGI2, NTRK1 and RAPGEF2; the complex is mainly formed at late endosomes in a nerve growth factor (NGF)-dependent manner (By similarity). Interacts with RAPGEF2; the interaction is strengthened after NGF stimulation (By similarity).

Interacts with PTPRS (By similarity). Interacts with USP36; USP36 does not deubiquitinate NTRK1 (PubMed:27445338). Interacts with GGA3 (PubMed:26446845).

Interacts with TSPAN1; this interaction promotes NTRK1 stability (By similarity)

Isoform TrkA-I is found in most non-neuronal tissues. Isoform TrkA-II is primarily expressed in neuronal cells. TrkA-III is specifically expressed by pluripotent neural stem and neural crest progenitors

The transmembrane domain mediates interaction with KIDINS220

The extracellular domain mediates interaction with NGFR

• Congenital insensitivity to pain with anhidrosis (CIPA)

  Characterized by a congenital insensitivity to pain, anhidrosis (absence of sweating), absence of reaction to noxious stimuli, self-mutilating behavior, and intellectual disability. This rare autosomal recessive disorder is also known as congenital sensory neuropathy with anhidrosis or hereditary sensory and autonomic neuropathy type IV or familial dysautonomia type II.

• Unknown disease