Cytokine that acts as a physiological ligand for receptor tyrosine kinases LTK and ALK, leading to their activation (PubMed:26418745, PubMed:26630010, PubMed:30061385, PubMed:33411331, PubMed:34646012, PubMed:34819673). Cytokine-binding is sufficient to activate LTK (PubMed:34646012). In contrast, ALKAL2-driven activation of ALK is coupled with heparin-binding to ALK (PubMed:34646012). Stimulation of ALK signaling is involved in neural development and regulation of energy expenditure (PubMed:34646012, PubMed:34819673).
