LTK

LTK is a member of the ros/insulin receptor family of tyrosine kinases. Tyrosine-specific phosphorylation of proteins is a key to the control of diverse pathways leading to cell growth and differentiation.

Full Name

Leukocyte Receptor Tyrosine Kinase

Function

Receptor with a tyrosine-protein kinase activity (PubMed:10445845, PubMed:20548102, PubMed:30061385).
Following activation by ALKAL1 or ALKAL2 ligands at the cell surface, transduces an extracellular signal into an intracellular response (PubMed:30061385, PubMed:34646012).
Ligand-binding to the extracellular domain induces tyrosine kinase activation, leading to activation of the mitogen-activated protein kinase (MAPK) pathway (PubMed:20548102).
Phosphorylates almost exclusively at the first tyrosine of the Y-x-x-x-Y-Y motif (By similarity).
The exact function of this protein is not known; studies with chimeric proteins demonstrate its ability to promote growth and specifically neurite outgrowth, and cell survival (PubMed:9223670, PubMed:18849880).
Involved in regulation of the secretory pathway involving endoplasmic reticulum (ER) export sites (ERESs) and ER to Golgi transport (PubMed:20548102).

Biological Process

Cell population proliferationManual Assertion Based On ExperimentIDA:UniProtKB
Cellular response to retinoic acidManual Assertion Based On ExperimentIMP:BHF-UCL
Negative regulation of apoptotic processManual Assertion Based On ExperimentIMP:UniProtKB
Phosphatidylinositol 3-kinase signalingManual Assertion Based On ExperimentIMP:UniProtKB
Positive regulation of cardiac muscle cell apoptotic processManual Assertion Based On ExperimentIDA:UniProtKB
Positive regulation of kinase activityManual Assertion Based On ExperimentIBA:GO_Central
Positive regulation of neuron projection developmentManual Assertion Based On ExperimentIMP:BHF-UCL
Protein phosphorylationManual Assertion Based On ExperimentIDA:UniProtKB
Regulation of cell population proliferationManual Assertion Based On ExperimentIBA:GO_Central
Regulation of neuron differentiationManual Assertion Based On ExperimentIBA:GO_Central
Signal transductionManual Assertion Based On ExperimentTAS:ProtInc
Transmembrane receptor protein tyrosine kinase signaling pathwayManual Assertion Based On ExperimentIBA:GO_Central

Cellular Location

Cell membrane

Involvement in disease

Genetic variations in LTK that cause up-regulation of the PI3K pathway may possibly contribute to susceptibility to abnormal proliferation of self-reactive B-cells and, therefore, to systemic lupus erythematosus (SLE) (PubMed:14695357). SLE is a chronic, inflammatory and often febrile multisystemic disorder of connective tissue, thought to represent a failure of the regulatory mechanisms of the autoimmune system (PubMed:14695357).

Topology

Extracellular: 17-424
Helical: 425-449
Cytoplasmic: 450-864

PTM

Phosphorylated at tyrosine residues by autocatalysis, which activates kinase activity.