Enables protein tyrosine kinase activity. Involved in several processes, including cellular response to molecule of fungal origin; histamine secretion by mast cell; and positive regulation of hypersensitivity. Located in perinuclear region of cytoplasm. Used to study arthus reaction. Human ortholog(s) of this gene implicated in agammaglobulinemia (multiple); isolated growth hormone deficiency type III; and lymphoma (multiple). Orthologous to human BTK (Bruton tyrosine kinase). [provided by Alliance of Genome Resources, Apr 2022]