Differential heat stress stability of epidermal growth factor receptor and erbB‐2 receptor tyrosine kinase activities

摘要: The epidermal growth factor (EGF) and erbB-2 receptors are structurally related membrane-bound tyrosine kinases. While these proteins exhibit close sequence homology, 50% overall 80% in the kinase domains, they respond very differently to heat stress. In NIH-3T3 or NR6 cells transfected with wild-type EGF-R incubated at 37 degrees C shocked 46 C, EGF binds its receptor stimulates autophosphorylation equivalent extents. At however, basal activity of is rapidly lost. When containing chimeric composed extracellular domain intracellular were stressed, 125I-EGF bound receptors, but did not stimulate autophosphorylation. decline EGF-stimulated dependent on length shock, nearly 100% lost after 60 min C. loss due degradation protein, nor it attributable a specific transmembrane from either receptors. Sensitivity stress also result denaturation this receptor's carboxy-terminal domain. Insertion into confers sensitivity resultant receptor. Thus, although domains show high degree secondary/tertiary structures would seem be stabilized distinct manners.