Expanding the Disorder-Function Paradigm in the C-Terminal Tails of Erbbs
Résumé
ErbBs are receptor tyrosine kinases involved not only in development, but also in a wide
variety of diseases, particularly cancer. Their extracellular, transmembrane, juxtamembrane, and
kinase folded domains were described extensively over the past 20 years, structurally and functionally.
However, their whole C-terminal tails (CTs) following the kinase domain were only described at
atomic resolution in the last 4 years. They were shown to be intrinsically disordered. The CTs are
known to be tyrosine-phosphorylated when the activated homo- or hetero-dimers of ErbBs are formed.
Their phosphorylation triggers interaction with phosphotyrosine binding (PTB) or Src Homology 2
(SH2) domains and activates several signaling pathways controling cellular motility, proliferation,
adhesion, and apoptosis. Beyond this passive role of phosphorylated domain and site display for
partners, recent structural and function studies unveiled active roles in regulation of phosphorylation
and interaction: the CT regulates activity of the kinase domain; different phosphorylation states have
different compaction levels, potentially modulating the succession of phosphorylation events; and
prolines have an important role in structure, dynamics, and possibly regulatory interactions. Here,
we review both the canonical role of the disordered CT domains of ErbBs as phosphotyrosine display
domains and the recent findings that expand the known range of their regulation functions linked to
specific structural and dynamic features.
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