Her3, also called ErbB3, is a type I membrane glycoprotein that is a member of the ErbB family of tyrosine kinase receptors.Her3 is expressed in keratinocytes, melanocytes, skeletal muscle cells, embryonic myoblasts and Schwann cells. Monomeric Her3 serves as a low affinity receptor for the heregulins (HRG).ation leads to a deletion of exons 2-7 of the EGFR gene and renders the mutant receptor incapable of binding any known ligand.