The selective coupling of G-protein-coupled receptors (GPCRs) to specific G proteins is critical to trigger the appropriate physiological response. However, the determinants of selective binding have remained elusive. Here we reveal the existence of a selectivity barcode (that is, patterns of amino acids) on each of the 16 human G proteins that is recognized by distinct regions on the approximately 800 human receptors. Although universally conserved positions in the barcode allow the receptors to bind and activate G proteins in a similar manner, different receptors recognize the unique positions of the G-protein barcode through distinct residues, like multiple keys (receptors) opening the same lock (G protein) using non-identical cuts. Considering the evolutionary history of GPCRs allows the identification of these selectivity-determining residues. These findings lay the foundation for understanding the molecular basis of coupling selectivity within individual receptors and G proteins.

The paper by Flock et al can be found here. More information can be found here.

Intrinsically disordered proteins (IDPs) can protect cells from diverse stresses by forming higher order assemblies such as reversible aggregates or granules. Recently, Boothby et al. show that IDPs protect tardigrades against desiccation by forming a glass-like amorphous matrix, highlighting that material properties of disordered proteins can confer adaptation during stress.

The paper by Chavali et al can be found here.

Nuclear magnetic resonance spectroscopy is transforming our views of proteins by revealing how their structures and dynamics are closely intertwined to underlie their functions and interactions. Compelling representations of proteins as statistical ensembles are uncovering the presence and biological relevance of conformationally heterogeneous states, thus gradually making it possible to go beyond the dichotomy between order and disorder through more quantitative descriptions that span the continuum between them.

The paper by Sormanni et al can be found here.

In the 1960s, Christian Anfinsen postulated that the unique three-dimensional structure of a protein is determined by its amino acid sequence. This work laid the foundation for the sequence-structure-function paradigm, which states that the sequence of a protein determines its structure, and structure determines function. However, a class of polypeptide segments called intrinsically disordered regions does not conform to this postulate. In this review, I will first describe established and emerging ideas about how disordered regions contribute to protein function. I will then discuss molecular principles by which regulatory mechanisms, such as alternative splicing and asymmetric localization of transcripts that encode disordered regions, can increase the functional versatility of proteins. Finally, I will discuss how disordered regions contribute to human disease and the emergence of cellular complexity during organismal evolution.

The review by M. Madan Babu can be found here.