Two GxxxG-Like Motifs Facilitate Promiscuous Interactions of the Human ErbB Transmembrane Domains

Members of the ErbB/HER family of epidermal growth factor receptor tyrosine kinases cross a membrane with a single transmembrane (TM) helix. ErbB receptors form diverse homo- and heterodimers, which substantially increases the signaling potential of ErbB receptors. The involvement of the ErbB TM domains in homo- and heterodimerization is largely enigmatic. In this study, we experimentally analyzed the potential role of two conserved GxxxG-like motifs for mediating and/or stabilizing homo- and hetero-oligomeric interactions of the human ErbB TM domains. Both motifs appear to be critical for homo- and hetero-oligomeric TM helix interactions. Consequently, multiple TM structures are possible for the various ErbB homo- and heterodimers, which might be critical for the formation and TM signaling of specific ErbB pairs in vivo.