Pro-neuregulin-1, membrane-bound isoform (NRG1)

Direct ligand for ERBB3 and ERBB4 tyrosine kinase receptors. Concomitantly recruits ERBB1 and ERBB2 coreceptors, leading to ligand-stimulated tyrosine phosphorylation and activation of the ERBB receptors.

The multiple isoforms perform varied functions like inducing growth and differentiation of epithelial, glial, neuronal, and skeletal muscle cells; inducing expression of acetylcholine receptor in synaptic vesicles through the formation of the neuromuscular junction; arousing lobuloalveolar budding and milk production in the mammary gland and inducing differentiation of mammary tumor cells; stimulating Schwann cell proliferation; implication in the development of the myocardium like trabeculation of the developing heart. Isoform 10 may play a role in sensory and motor neuron development.