ErbB3/Her3 Proteins and Enzymes

ErbB3, also called Her3 (human epidermal growth factor receptor 3) in humans, is a type I transmembrane glycoprotein that is a member of the ErbB family of tyrosine kinase receptors. ErbB3 binds neuregulins NRG1 and NRG2, but lacks a working kinase domain; heterodimerization with another ErbB receptor is required for signaling. ErbB3 is important in development of Schwann cells, neural crest cells, heart valves and the sympathetic nervous system. When expressed with ErbB2 in breast, skin, ovary and gastrointestinal tumors, ErbB3 is a potent mitogen.