PEAK pseudokinases (PEAK1, PEAK2 and PEAK3) are important protein scaffolds that regulate cell migration, invasion and proliferation by recruiting signalling effectors at the cytoskeleton [1, 2]. Despite lacking catalytic activity, alteration in the expression level of PEAK family members is associated with several type of aggressive cancers. An emerging thread of PEAK family function is the ability to utilise homo- and hetero-dimerisation to dynamically integrate and diversify cellular signals.
Our lab was the first to structurally reveal a unique dimer-dependent scaffolding activity of PEAK pseudokinases [3]. PEAK pseudokinases additionally possess an N‑terminal intrinsically disordered region crucial for dynamic recruitment of signaling partners, but the dynamic PEAK interactome remains relatively poorly understood.
This dearth of knowledge is particularly pronounced for PEAK3, which was only very recently identified [4, 5]. An important interactor of PEAK3 has been identified as the signalling adapter protein CrkII.5 We and others recently described additional PEAK3 interactors including the adapter protein Grb2, epidermal growth factor receptor (EGFR), the integrin-associated tyrosine kinase PYK2 and Arf-GAP family member ASAP1 [6, 7].
In this presentation, I will outline recent work in which we have applied an integrative structural approach to identify and molecularly characterise a novel regulatory site in the intrinsically disordered region of PEAK pseudokinases which can bind to 14-3-3 proteins [1]. Using biophysical and cellular approaches, we show that 14-3-3 binding to PEAK3 represents a molecular switch to regulate PEAK3/Crk signalling and downstream cell growth/migration pathways. By characterizing the key interactors that drive the formation of PEAK functional signalling networks, we rationalize why dimerization of PEAKs has a crucial function in signal transduction and demonstrate how signal specificity is achieved amongst the family [1].