The region containing residues I649 − L659 of the epidermal growth factor receptor (EGFR) juxtamembrane domain (JM) specifically interacts with PI(4,5)P₂-or phosphatidylserine-containing membranes, suggesting that membrane binding may affect JM dimerization and, therefore, regulate EGFR kinase activation.

Overactivation of the epidermal growth factor receptor (EGFR) is critical for the development of multiple cancers. Previous studies have shown that the cell membrane is a key regulator of EGFR kinase activity through its interaction with the EGFR juxtamembrane domain (JM). However, the lipid recognition specificity of EGFR-JM and its interaction details remain unclear. Using lipid strip and liposome pulldown assays, we showed that EGFR-JM could specifically interact with PI(4,5)P₂-or phosphatidylserine-containing membranes. We further characterized the JM–membrane interaction using NMR-titration-based chemical shift perturbation and paramagnetic relaxation enhancement analyses, and found that residues I649 − L659 comprised the membrane-binding site. Furthermore, the membrane-binding region contains the predicted dimerization motif of JM, ⁶⁵⁵LRRLL⁶⁵⁹, suggesting that membrane binding may affect JM dimerization and, therefore, regulate kinase activation.

X-ray crystallography was used to determine an active-like dimer of the ligand-binding domain of GluK2, locating the positive allosteric modulator BPAM344 within the dimeric interface. Selected residues T535 and Q786 differing between GluK2 and GluA2 were investigated with calcium-sensitive fluorescence-based assays on transiently transfected cells. A three-fold increase in BPAM344 potency occurred with the double mutant T535S-Q786S in GluK2(Q).

Kainate receptors belong to the family of ionotropic glutamate receptors and contribute to the majority of fast excitatory neurotransmission. Consequently, they also play a role in brain diseases. Therefore, understanding how these receptors can be modulated is of importance. Our study provides a crystal structure of the dimeric ligand-binding domain of the kainate receptor GluK2 in complex with L-glutamate and the small-molecule positive allosteric modulator, BPAM344, in an active-like conformation. The role of Thr535 and Gln786 in modulating GluK2 by BPAM344 was investigated using a calcium-sensitive fluorescence-based assay on transiently transfected cells expressing GluK2 and mutants hereof. This study may aid in the design of compounds targeting kainate receptors, expanding their potential as targets for the treatment of brain diseases.

Protein components of the germ granules, Aubergine (Aub) and Pyruvate Kinase (PyK), use different modes to associate with Tudor (Tud) protein, which contains 11 Tud domains. Aub binds to a single Tud domain and PyK requires two Tud domains. Aub and PyK compete for binding to Tud in vitro and form separate clusters within a granule in vivo, thereby minimizing the competition.

Membraneless organelles are RNA–protein assemblies which have been implicated in post-transcriptional control. Germ cells form membraneless organelles referred to as germ granules, which contain conserved proteins including Tudor domain-containing scaffold polypeptides and their partner proteins that interact with Tudor domains. Here, we show that in Drosophila, different germ granule proteins associate with the multi-domain Tudor protein using different numbers of Tudor domains. Furthermore, these proteins compete for interaction with Tudor in vitro and, surprisingly, partition to distinct and poorly overlapping clusters in germ granules in vivo. This partition results in minimization of the competition. Our data suggest that Tudor forms structurally different configurations with different partner proteins which dictate different biophysical properties and phase separation parameters within the same granule.

The circumsporozoite protein of Plasmodium falciparum (Pf-CSP) contains two nuclear localization signals (NLSs). The lysine and arginine residues in both NLSs are essential for Pf-CSP interaction with importin-α, aiding Pf-CSP's nuclear translocation. Both NLSs are vital for nuclear localization, with individual NLSs resulting in weaker localization. Pf-CSP also contains a distinct nuclear export signal motif that coordinates the protein nucleocytoplasmic shuttling mechanisms.

Secretory proteins of Plasmodium exhibit differential spatial and functional activity within the host cell nucleus. However, the nuclear localization signals (NLSs) for these proteins remain largely uncharacterized. In this study, we have identified and characterized two NLSs in the circumsporozoite protein of Plasmodium falciparum (Pf-CSP). Both NLSs in the Pf-CSP contain clusters of lysine and arginine residues essential for specific interactions with the conserved tryptophan and asparagine residues of importin-α, facilitating nuclear translocation of Pf-CSP. While the two NLSs of Pf-CSP function independently and are both crucial for nuclear localization, a single NLS of Pf-CSP leads to weak nuclear localization. These findings shed light on the mechanism of nuclear penetrability of secretory proteins of Plasmodium proteins.